Glossary

Vocal intensity rises by roughly 8 to 9 dB for each doubling of lung pressure above phonation threshold, less than the 12 dB a pure pressure-squared law would predict.

Appears in: Variation of Intensity with Adduction, Lung Pressure, and F₀ (Ch. 9)

The mode in which the whole fold moves laterally in phase with no vertical phase difference, the pattern of a one-mass model. On its own it cannot sustain oscillation without vocal tract inertance.

Appears in: Normal Modes of Vibration in Vocal Fold Tissues (Ch. 4)

The vocal fold mode with one half-wavelength along the fold and one vertically, so the lower margin leads the upper. It produces the convergent–divergent alternation of normal phonation and couples most efficiently to airflow.

Appears in: Criteria for Oscillation (Ch. 4) · The Swing as a Simple Oscillator (Ch. 4) · A Mass-Spring Oscillator (Ch. 4) · Normal Modes of Vibration in Vocal Fold Tissues (Ch. 4) · Clinical and Pedagogical Issues (Oscillation) (Ch. 4) · Maintaining Adequate Hydration (Ch. 4) and 1 more

Pre-phonatory glottal half-width divided by vibrational amplitude. Values below about 0.3 predict modal voice, above about 0.5 predict falsetto, with mixed quality in between.

Appears in: Temporal Gap and Spectral Slope (Ch. 10) · The Modal-Falsetto Transition (Ch. 10) · Involuntary Register Transitions: Two Hypotheses (Ch. 10) · Clinical and Pedagogical Issues (Ch. 10)

The ratio of pressure to volume velocity, equal to ρc divided by cross-sectional area. A narrower section has higher impedance, so a wave entering a constriction reflects with positive polarity and pressure rises.

The total acoustic energy radiated per second, in watts. It is a property of the source and does not depend on where it is measured; conversational speech radiates about ten to a hundred microwatts.

Appears in: Some Definitions of Terms (Ch. 9) · Radiation of Sound (Ch. 9) · Sound Intensity Level and Sound Pressure Level (Ch. 9) · Radiation from Simple Sources (Ch. 9) · Variation of Intensity with Adduction, Lung Pressure, and F₀ (Ch. 9) · Glottal Source Power and Inverse Filtering (Ch. 9) and 20 more

Stress generated inside a muscle by cross-bridge cycling, added to the passive stress from stretch. It scales with neural activation and peaks at an intermediate fiber length.

Appears in: Fundamentals of Tissue Viscoelasticity (Ch. 2) · Active Stress of Muscles (Ch. 2) · The Body-Cover Model of F₀ Control (Ch. 8) · Active Tissue in Vibration (Ch. 8) · Hypothesis Two: Maximum Active Thyroarytenoid Stress (Ch. 10)

Lung pressure multiplied by airflow, the rate at which the respiratory system supplies energy to the larynx. In speech it is on the order of a watt or less.

Appears in: Measurement of Lung Pressure (Ch. 3) · The Pulmonary System (Ch. 3) · Pulmonary Power (Ch. 3) · Finding the Best Speaking Pitch (Ch. 8) · Variation of Intensity with Adduction, Lung Pressure, and F₀ (Ch. 9) · Vocal Efficiency (Ch. 9) and 4 more

The air pressure in the alveoli, which during phonation is transmitted to the subglottal space. It is the driving pressure for vocal fold vibration.

Also: alveolar pressure, lung pressure

Appears in: Fluid Pressure (Ch. 3) · Pascal's Law (Ch. 3) · Lung (Alveolar) Pressure (Ch. 3) · Thoracic, Pleural, and Abdominal Pressure (Ch. 3) · Measurement of Lung Pressure (Ch. 3) · The Pulmonary System (Ch. 3) and 22 more

Vibrational amplitude divided by fold length. Children may have a high ratio, which makes pitch rise with loudness and explains their difficulty separating the two.

Appears in: Childhood (Ch. 7) · The Amplitude-to-Length Ratio (Ch. 8)

Having different mechanical properties in different directions. Vocal fold tissue is much stiffer along its fibers than across them.

Also: anisotropic

Appears in: The Mechanical System (Ch. 2) · Elements of Continuum Mechanics (Ch. 2) · Constitutive Equations (Ch. 2) · Fundamentals of Tissue Viscoelasticity (Ch. 2)

A frequency at which a side branch such as the nasal cavity absorbs energy, producing a dip in the spectrum. Nasalized vowels show anti-resonances between their formants.

Also: antiresonance

Appears in: Reflection Coefficients (Ch. 6) · Frequency Spectrum of the Resonating Tube (Ch. 6) · Vowel Shapes (Ch. 6) · Sources of Sound (Ch. 5) · Frequency Spectra & Spectral Slope (Ch. 5) · The Meaning of a Spectrum (Ch. 5) and 3 more

The paired pyramidal cartilages on the posterior cricoid. Their vocal processes anchor the vocal folds and their muscular processes receive the adductor and abductor muscles, so their rocking and sliding opens and closes the glottis.

Also: arytenoid cartilage, arytenoids

Appears in: Hard-Tissue Morphology (Ch. 1) · Laryngeal Cartilages (Ch. 1) · Intrinsic Muscles of the Larynx (Ch. 1) · Morphology of Vocal Fold Soft Tissue (Ch. 1) · Use of the Silent-H or Sigh for Voice Onset and Release (Ch. 4) · The Glottal Source Function (Ch. 5) and 5 more

Turbulence noise generated by air rushing through an incompletely closed glottis. It adds a continuous noise floor to the harmonic spectrum and gives breathy voice its character.

Appears in: Sources of Sound (Ch. 5) · The Meaning of a Spectrum (Ch. 5) · Sources of Fluctuation and Perturbation (Ch. 11)

The three soft-tissue processes of aging: wasting of cells, malfunction of cells, and excessive fluid in tissue. Thyroarytenoid atrophy bows the folds and produces a weaker, breathier voice.

Also: atrophy, dystrophy, edema

Appears in: Critical Periods of Vocal Change (Ch. 7) · Maturity and Advanced Age (Ch. 7) · Laryngeal Cartilages (Ch. 1) · Muscles of the Larynx (Ch. 1) · Intrinsic Muscles of the Larynx (Ch. 1) · Extrinsic Muscles of the Larynx (Ch. 1) and 29 more

A filter that passes a range of frequencies and attenuates those outside it. Sweeping a band-pass filter across a signal is how the classic sound spectrograph measured a spectrum.

Also: bandpass filter

Appears in: Filters and Filtering (Ch. 6) · The Sound Spectrograph (Ch. 6)

In phonation: The negative pressure created by high-velocity air in the narrow glottis, which helps draw the folds together. Because it is the same on opening and closing, it cannot by itself sustain oscillation.

Appears in: Classical Description of Vocal Fold Oscillation (Ch. 4) · Types of Oscillation (Ch. 4) · Mechanisms for Self-Sustained Vocal Fold Oscillation (Ch. 4) · Vocal Tract Inertance: The One-Mass Model (Ch. 4) · Nonuniform Tissue Movement: Multimass Models (Ch. 4) · Time-Varying Glottal Pressure and Flow (Ch. 4) and 7 more

Along a lossless streamline, pressure plus kinetic energy per unit volume (½ρv²) is constant, so where the flow speeds up the pressure falls. It explains the low pressure inside the narrow glottis.

Also: Bernoulli's principle, Bernoulli's equation

Appears in: Conservation Laws for Flow in Ducts (Ch. 3) · Conservation of Energy (Bernoulli's Law) (Ch. 3) · Nonuniform Tissue Movement: Multimass Models (Ch. 4) · Time-Varying Glottal Pressure and Flow (Ch. 4)

A sudden qualitative change in a system's behavior as a control parameter such as pressure or asymmetry crosses a threshold, for example from periodic oscillation to period doubling or chaos.

Appears in: Jitter and Shimmer (Ch. 11) · Nonstationarity and Trends (Ch. 11) · Bifurcations and Chaos (Ch. 11) · Irregularity in Voice: Another Moment of Frivolity (Ch. 11) · Lung (Alveolar) Pressure (Ch. 3) · Periodicity (Ch. 4) and 1 more

The extension in which the thyroarytenoid body also vibrates. Active muscle stress adds stiffness, so thyroarytenoid contraction can raise F₀ in loud, modal phonation even though it shortens the folds.

Also: body-cover, body-cover theory

Appears in: The Cover Model of F₀ Control (Ch. 8) · Analogies with Vibrating Strings and Ribbons (Ch. 8) · Quantitative F₀ Analysis for the Cover Model (Ch. 8) · The Body-Cover Model of F₀ Control (Ch. 8) · Active Tissue in Vibration (Ch. 8) · Muscle Activation Plot for the Body-Cover Model (Ch. 8) and 16 more

The region between D₄ and G₄ that is very hard to sing through, especially for males, unless it is widened with middle (head) register.

Appears in: Epilogue (Ch. 10)

At constant temperature the product of pressure and volume of a gas is constant. Expanding the thorax lowers lung pressure and draws air in; compressing it raises pressure and drives air out.

Appears in: Lung (Alveolar) Pressure (Ch. 3) · The Physical Process of Breathing (Boyle's Law) (Ch. 3)

Aerodynamic sign: Phonation with an incompletely closed glottis, marked by mean airflow well above the normal range (above about 0.2 liters per second), low glottal resistance and added turbulence noise.

Also: breathy voice

Appears in: Flow Resistance (Glottal Resistance) (Ch. 3) · Proper Use of Airflow (Ch. 3) · Muscles of the Larynx (Ch. 1) · Intrinsic Muscles of the Larynx (Ch. 1) · Morphology of Vocal Fold Soft Tissue (Ch. 1) · Vascularity and Innervation of the Larynx (Ch. 1) and 23 more

The posterior portion of the glottis between the vocal processes and the arytenoid bodies. It is closed by the interarytenoid muscles and does not vibrate.

The auditory system's habit of sorting a physical continuum into discrete categories, as with the colors of a rainbow or voiced versus voiceless consonants. Register perception is an example.

Appears in: Perception of Vocal Registers (Ch. 10) · Temporal Gap and Spectral Slope (Ch. 10) · The Pulse-Modal Transition (Ch. 10) · The Modal-Falsetto Transition (Ch. 10) · Register Terminology (Ch. 10) · The F1-F2 Vowel Chart (Ch. 6)

A measure of how strongly periodic a voice is, taken from the cepstrum. It tolerates nonstationarity and irregularity better than jitter and shimmer and is increasingly used clinically.

Also: CPP

Appears in: Signal Typing and Physical Measures (Ch. 11) · Nonstationarity and Trends (Ch. 11) · Clinical and Pedagogical Issues (Perturbations) (Ch. 11) · Test Utterances (Ch. 11) · Frequency Spectra & Spectral Slope (Ch. 5) · The Spectral Slope (Ch. 5) and 3 more

Hollien's description of vocal aging in which male F₀ rises and female F₀ falls slightly, converging as the hormonal differences that separated them at puberty fade.

Appears in: Maturity and Advanced Age (Ch. 7)

The mathematical relation between stress and strain (and strain rate) that characterizes a particular material, such as Hooke's law for a linear solid or stress proportional to strain rate for a viscous fluid.

Appears in: Elements of Continuum Mechanics (Ch. 2) · Constitutive Equations (Ch. 2) · Time Dependence and Viscosity (Ch. 2)

For incompressible flow in a duct, velocity times cross-sectional area is the same at every point. Air must therefore speed up about a hundredfold as it passes from the trachea through the narrow glottis.

Also: continuity equation, law of continuity

Appears in: Conservation Laws for Flow in Ducts (Ch. 3) · Continuity Law of Incompressible Flow (Ch. 3) · Conservation of Energy (Bernoulli's Law) (Ch. 3) · Time-Varying Glottal Pressure and Flow (Ch. 4)

A glottal shape that narrows from bottom to top, occurring during the opening phase when the lower margin leads. Mean intraglottal pressure is high, driving the folds outward.

Appears in: Nonuniform Tissue Movement: Multimass Models (Ch. 4)

The description of pitch control when only the cover vibrates, as in soft voice and falsetto. F₀ is set by the passive stress in the cover, which the cricothyroid raises by elongation.

Appears in: The Cover Model of F₀ Control (Ch. 8) · Analogies with Vibrating Strings and Ribbons (Ch. 8) · Quantitative F₀ Analysis for the Cover Model (Ch. 8) · The Body-Cover Model of F₀ Control (Ch. 8) · Active Tissue in Vibration (Ch. 8) · Muscle Activation Plot for the Body-Cover Model (Ch. 8)

A functional division of the vocal fold into a pliable cover (epithelium and the superficial, loose lamina propria) that carries the mucosal wave, and a stiffer body (vocal ligament and thyroarytenoid muscle) that can adjust its own stiffness.

Also: cover-body model, cover-body

Appears in: Morphology of Vocal Fold Soft Tissue (Ch. 1) · Phonation Threshold Pressure (Ch. 9)

A rough quality with some characteristics of vocal fry but perceived as roughness rather than pulses; it is not a register and may reflect subharmonic patterns in the glottal waveform.

Also: creak, creaky phonation

Appears in: The Pulse-Modal Transition (Ch. 10) · Epilogue (Ch. 10) · Register Terminology (Ch. 10) · Vocal Registers: Some Iowa Corn (Ch. 10) · A Fundamental Frequency Profile (Ch. 11)

The gradual increase in length of a tissue held under a constant load, like taffy slowly stretching. It is the counterpart of stress relaxation.

Appears in: Elements of Continuum Mechanics (Ch. 2) · Time Dependence and Viscosity (Ch. 2) · One-Dimensional Stress-Strain Relations in Vocal Fold Tissue (Ch. 2) · Biomechanical Sources (Ch. 11)

The complete ring of cartilage at the base of the larynx, sitting on top of the trachea. It carries the arytenoids on its posterior plate and articulates with the thyroid cartilage at the cricothyroid joints.

Also: cricoid

Appears in: Some Anatomical Terminology (Ch. 1) · Hard-Tissue Morphology (Ch. 1) · Laryngeal Cartilages (Ch. 1) · Intrinsic Muscles of the Larynx (Ch. 1) · Maturity and Advanced Age (Ch. 7) · Mechanics of Vocal Fold Elongation (Ch. 8) and 2 more

The paired joint between the inferior horns of the thyroid cartilage and the cricoid. Rotation (and some sliding) here lengthens or shortens the vocal folds, which is the primary means of changing pitch.

Appears in: Hard-Tissue Morphology (Ch. 1) · Laryngeal Cartilages (Ch. 1) · Intrinsic Muscles of the Larynx (Ch. 1) · Maturity and Advanced Age (Ch. 7) · Mechanics of Vocal Fold Elongation (Ch. 8) · Limitations in F0 Range (Ch. 8)

The intrinsic muscle running from the cricoid arch to the thyroid cartilage (pars recta and pars obliqua). Contraction rotates the cartilages toward each other, elongating and tensing the vocal folds to raise pitch. It is the one intrinsic muscle supplied by the superior laryngeal nerve.

Also: cricothyroid, CT

Appears in: Some Anatomical Terminology (Ch. 1) · Hard-Tissue Morphology (Ch. 1) · Laryngeal Cartilages (Ch. 1) · Muscles of the Larynx (Ch. 1) · Intrinsic Muscles of the Larynx (Ch. 1) · Extrinsic Muscles of the Larynx (Ch. 1) and 48 more

The fundamental frequency, about 70 Hz, below which the ear resolves individual glottal bursts and silences. It marks the pulse–modal boundary and depends on auditory temporal resolution rather than laryngeal mechanics.

Appears in: Perception of Vocal Registers (Ch. 10) · Temporal Gap and Spectral Slope (Ch. 10) · The Pulse-Modal Transition (Ch. 10)

The loss of oscillation energy to friction or viscosity. Without a source of energy input, damping brings any free oscillation to rest.

Appears in: Classical Description of Vocal Fold Oscillation (Ch. 4) · Simple Oscillators (Ch. 4) · Criteria for Oscillation (Ch. 4) · Types of Oscillation (Ch. 4) · The Swing as a Simple Oscillator (Ch. 4) · A Mass-Spring Oscillator (Ch. 4) and 27 more

The fraction of the vibrating tissue depth that is thyroarytenoid muscle. Below about 0.3 the cover dominates and thyroarytenoid contraction lowers pitch; above about 0.5 the body dominates and it raises pitch.

Appears in: The Body-Cover Model of F₀ Control (Ch. 8) · Active Tissue in Vibration (Ch. 8)

The dome-shaped muscle separating thorax and abdomen. Its contraction flattens the dome, enlarging the thorax for inspiration; it is not an expiratory muscle.

Appears in: Pascal's Law (Ch. 3) · Lung (Alveolar) Pressure (Ch. 3) · Thoracic, Pleural, and Abdominal Pressure (Ch. 3) · The Physical Process of Breathing (Boyle's Law) (Ch. 3) · Airflow in Speech and Nonspeech (Ch. 3) · Clinical and Pedagogical Notes on Breathing (Ch. 3) and 7 more

The perception of two simultaneous pitches, produced by asynchronous oscillation of the two folds, different vibratory modes, or ventricular fold involvement. Biphonation names the production mechanism.

Also: diplophonic

Appears in: Perturbations and Fluctuations (Ch. 11) · Jitter and Shimmer (Ch. 11) · Periodicity and Modulation (Ch. 11) · Sources of Fluctuation and Perturbation (Ch. 11) · Biomechanical Sources (Ch. 11) · Signal Typing and Physical Measures (Ch. 11) and 13 more

A glottal shape that widens from bottom to top, occurring during the closing phase. Mean intraglottal pressure is low, so little energy is taken from the folds as they move inward.

Appears in: Nonuniform Tissue Movement: Multimass Models (Ch. 4)

'C in chest': a tenor's high C sung in modal register, near the upper limit that maximum thyroarytenoid stress allows.

Appears in: Involuntary Register Transitions: Two Hypotheses (Ch. 10)

The lumped spring and mass that give a vibrating fold the same natural frequency as a string. Effective stiffness is proportional to tension and inversely proportional to length squared.

Also: effective stiffness, effective mass

Appears in: Descriptive Overview of F₀ Control (Ch. 8) · Vocal Fold Stiffness and Mass (Ch. 8) · Biological Factors Influencing Stiffness (Ch. 8) · The Body-Cover Model of F₀ Control (Ch. 8) · Active Tissue in Vibration (Ch. 8) · Muscle Activation Plot for the Body-Cover Model (Ch. 8) and 9 more

The passive tendency of the stretched lungs and rib cage to return toward their resting volume. At high lung volumes it supplies more pressure than speech needs, so inspiratory muscles must brake it.

Appears in: Pascal's Law (Ch. 3) · Thoracic, Pleural, and Abdominal Pressure (Ch. 3) · The Physical Process of Breathing (Boyle's Law) (Ch. 3) · Airflow in Speech and Nonspeech (Ch. 3) · Clinical and Pedagogical Notes on Breathing (Ch. 3) · Why Teach Breathing? (Ch. 3) and 5 more

A non-invasive technique that passes a tiny current across the neck to track vocal fold contact area during vibration, revealing closing and opening timing without a camera.

Also: EGG, electroglottograph, electroglottographic

Appears in: Some Instrumentation for Clinical Use (Ch. 4) · Proper Use of Airflow (Ch. 3) · Glottal Source Power and Inverse Filtering (Ch. 9) · Dependence of Glottal Source Power on Adduction (Ch. 9) · Clinical and Pedagogical Issues (Intensity) (Ch. 9) · The Hazards of Pressed Voice (Ch. 9) and 4 more

Of laryngeal muscles: Recording electrical activity from muscles with hooked-wire electrodes. Across studies the cricothyroid correlates most strongly with F₀ and the thyroarytenoid second.

Also: EMG, electromyographic

Appears in: Investigations with Electromyography (Ch. 8) · The Body-Cover Model of F₀ Control (Ch. 8) · Active Tissue in Vibration (Ch. 8) · Muscle Activation Plot for the Body-Cover Model (Ch. 8) · Dependence of Glottal Source Power on Adduction (Ch. 9) · Hypothesis Two: Maximum Active Thyroarytenoid Stress (Ch. 10) and 4 more

Constriction of the tube just above the vocal folds, which raises the impedance seen by the glottis and is the key adjustment behind the singer's formant.

Appears in: Variation of Intensity with Vocal Tract Adjustments (Ch. 9) · Vocal Tract Transfer Gain (Ch. 9) · Vocal Ring (the Singer's Formant) (Ch. 9)

Muscles with one attachment outside the larynx (the strap muscles such as sternothyroid, thyrohyoid, sternohyoid, omohyoid, plus the suprahyoids). They raise, lower and stabilize the larynx as a whole rather than moving the vocal folds directly.

Also: extrinsic laryngeal muscle

Appears in: The Hyoid Bone (Ch. 1) · Extrinsic Muscles of the Larynx (Ch. 1) · Investigations with Electromyography (Ch. 8) · Mechanics of Vocal Fold Elongation (Ch. 8)

The empirical hyperbola relating average speaking fundamental frequency in hertz to membranous length in millimeters. It predicts about 106 Hz for a 16 mm male fold and 170 Hz for a 10 mm female fold.

Appears in: Fundamental Frequency and Vocal Fold Length (Ch. 7) · Childhood (Ch. 7)

A plot of the first formant against the second for each vowel. F₁ falls as the tongue rises; F₂ rises as the tongue moves forward, so the chart mirrors the traditional vowel quadrilateral.

Also: vowel chart, F1-F2 chart

Appears in: Articulatory and Acoustic Descriptions of Vowels (Ch. 6) · The F1-F2 Vowel Chart (Ch. 6) · The Sound Spectrograph (Ch. 6) · Rules for Modifying Vowels (Ch. 6) · Clinical and Pedagogical Issues (Ch. 10)

The German system of operatic subclassification (lyric, dramatic, spinto, coloratura and so on) that matches voices to repertoire by weight, color and agility as well as range.

Appears in: Classification Based on Secondary Factors (Ch. 7) · Summary of Classification Methods (Ch. 7)

The light register with a steep spectral slope, minimal thyroarytenoid activity and incomplete or gentle closure. Only the cover vibrates against a stiff, elongated fold.

Also: falsetto

Appears in: Perception of Vocal Registers (Ch. 10) · Temporal Gap and Spectral Slope (Ch. 10) · The Modal-Falsetto Transition (Ch. 10) · Involuntary Register Transitions: Two Hypotheses (Ch. 10) · Hypothesis Two: Maximum Active Thyroarytenoid Stress (Ch. 10) · Clinical and Pedagogical Issues (Ch. 10) and 35 more

Muscle fibers with fast myosin isoforms that contract quickly and, in the laryngeal adductors, remain unusually fatigue-resistant. They underlie rapid glottal closure and pitch change.

Also: fast-twitch fiber, fast-twitch muscle fibers

Appears in: A Brief Introduction to Muscles (Ch. 2) · Muscles of the Larynx (Ch. 1)

The tracheal resonance, about 500 to 600 Hz in living subjects. Its pressure phase relative to glottal opening reinforces vibration at some fractions of its frequency and disrupts it at others.

Also: subglottal formant, subglottal resonance

Appears in: The Modal-Falsetto Transition (Ch. 10) · Involuntary Register Transitions: Two Hypotheses (Ch. 10) · Hypothesis One: Subglottal Resonances (Ch. 10) · Hypothesis Two: Maximum Active Thyroarytenoid Stress (Ch. 10) · Clinical and Pedagogical Issues (Ch. 10) · Register Equalization by Vocal Tract Adjustments (Ch. 10) and 5 more

Phonation with moderate adduction and a strong acoustic flow component, giving high output for low effort and collision stress. It is the target quality in much voice therapy and pedagogy.

Also: flow phonation, resonant voice, resonant phonation

Appears in: Dependence of Glottal Source Power on Adduction (Ch. 9) · Phonation Threshold Pressure (Ch. 9) · Dependence of Glottal Source Power on Lung Pressure and F0 (Ch. 9) · Vocal Efficiency (Ch. 9) · Glottal Efficiency (Ch. 9) · Power Losses (Ch. 9) and 7 more

The pressure drop divided by the flow through a constriction. The glottis is the largest resistance in the airway, and its value rises steeply as the glottal area shrinks.

Also: glottal resistance

Appears in: The Pulmonary System (Ch. 3) · The Physical Process of Breathing (Boyle's Law) (Ch. 3) · Airflow in Speech and Nonspeech (Ch. 3) · Conservation Laws for Flow in Ducts (Ch. 3) · Flow Resistance (Glottal Resistance) (Ch. 3) · Why Teach Breathing? (Ch. 3) and 17 more

A slower, more regular modulation of fundamental frequency or amplitude spanning many cycles, typically at 3 to 15 Hz. Vibrato and tremor are fluctuations.

Appears in: Some Definitions (Ch. 11) · Perturbations and Fluctuations (Ch. 11) · Variability (Ch. 11) · Jitter and Shimmer (Ch. 11) · Periodicity and Modulation (Ch. 11) · Sources of Fluctuation and Perturbation (Ch. 11) and 18 more

A resonance of the vocal tract, seen as a peak in the spectral envelope. Formant frequencies depend on the tract's length and shape, not on the source.

Appears in: Sound Propagation in Tubes (Ch. 6) · Acoustic Impedance and Reflection (Ch. 6) · Reflection Coefficients (Ch. 6) · Quarter-Wave Resonance (Ch. 6) · Half-Wave Resonance (Ch. 6) · Frequency Spectrum of the Resonating Tube (Ch. 6) and 64 more

The width of a formant peak, set by energy losses in the tract (wall vibration, viscosity, radiation). Wider bandwidths mean weaker, broader peaks.

Appears in: Reflection Coefficients (Ch. 6) · Frequency Spectrum of the Resonating Tube (Ch. 6) · Formant Bandwidth (Ch. 6) · Vowel Shapes (Ch. 6) · A Three-Tube Approximation (Ch. 6) · Spectral Analysis of Vowels (Ch. 6) and 12 more

Aligning a harmonic with a formant to exploit the resonance gain. Sopranos raise F₁ toward a high F₀ by opening the jaw; lower voices often tune the second harmonic to F₁.

Appears in: Variation of Intensity with Vocal Tract Adjustments (Ch. 9) · Formant Tuning (Ch. 9) · Combined Intensity Changes with Lung Pressure and F0 (Ch. 9) · The Voice Range Profile (Ch. 9) · Vocal Ring (the Singer's Formant) (Ch. 9) · Vocal Efficiency (Ch. 9) and 15 more

The decomposition of any periodic waveform into a sum of sinusoids at harmonic frequencies. It is the mathematical basis of the spectrum.

Appears in: The Meaning of a Spectrum (Ch. 5) · The Spectral Slope (Ch. 5) · Sinusoidal Waves (Ch. 5) · Graphical and Mathematical Representations of Oscillatory Movement (Ch. 4) · Periodicity (Ch. 4) · Simple Harmonic Motion (Ch. 4)

The mathematical operation that converts a time waveform into its spectrum, or a spectrum back into a waveform. It underlies all spectral analysis of voice.

Appears in: Frequency Spectrum of the Resonating Tube (Ch. 6) · Filters and Filtering (Ch. 6) · Periodicity (Ch. 4) · Frequency Spectra & Spectral Slope (Ch. 5) · The Meaning of a Spectrum (Ch. 5) · Periodicity and Modulation (Ch. 11) and 3 more

The repetition rate of the glottal pulses, in hertz, and the first harmonic of the source spectrum. It is the physical correlate of pitch.

Also: F₀, F0

Appears in: Sources of Sound (Ch. 5) · Frequency Spectra & Spectral Slope (Ch. 5) · The Meaning of a Spectrum (Ch. 5) · The Spectral Slope (Ch. 5) · Propagation Velocity (Ch. 5) · Sinusoidal Waves (Ch. 5) and 107 more

The parameter in the elongation equation that sets how much strain a given difference in muscle activities produces. It depends on joint geometry and varies between individuals.

Appears in: Mechanics of Vocal Fold Elongation (Ch. 8)

Radiated acoustic power divided by the aerodynamic power supplied by the lungs. It is typically a fraction of one percent, because most energy is lost to tissue viscosity, collision and air friction.

Appears in: Vocal Efficiency (Ch. 9) · Efficiency in a Multipurpose Machine (Ch. 9) · Glottal Efficiency (Ch. 9) · Power Losses (Ch. 9) · Problems with Glottal Efficiency Definitions and Calculations (Ch. 9) · Finding the Best Speaking Pitch (Ch. 8) and 1 more

The pulse of air volume velocity through the glottis over one cycle. Its shape, not just its rate, determines the harmonic content of the voice source.

Also: glottal flow, glottal airflow waveform

Appears in: Sources of Sound (Ch. 5) · The Glottal Source Function (Ch. 5) · The Spectral Slope (Ch. 5) · The Space-Time Concept of a Wave (Ch. 5) · Wave Interference and Standing Waves (Ch. 5) · Conservation Laws for Flow in Ducts (Ch. 3) and 19 more

The average F₀ a person actually uses in connected speech, a learned behavior that may or may not match the pitch that is physiologically most efficient.

Also: habitual pitch

Appears in: Effect of Lung Pressure on F0 (Ch. 8) · Clinical and Pedagogical Issues (F0) (Ch. 8) · Finding the Best Speaking Pitch (Ch. 8) · Role Models and Culture (Ch. 7) · Clinical and Pedagogical Issues (Classification) (Ch. 7) · Summary of Classification Methods (Ch. 7) and 7 more

A tube open (or closed) at both ends, which resonates when its length is a whole number of half wavelengths. Its resonances form a complete harmonic series, unlike the quarter-wave tube.

Also: half-wavelength resonator, half wave resonator

Appears in: Half-Wave Resonance (Ch. 6)

Starting a tone from fully closed vocal folds so pressure builds and blows them apart. It produces irregular early cycles and higher collision stress than a gently abducted onset.

Also: hard attack

Appears in: Clinical and Pedagogical Issues (Oscillation) (Ch. 4) · Use of the Silent-H or Sigh for Voice Onset and Release (Ch. 4) · Proper Use of Airflow (Ch. 3) · Secondary Sound Sources in the Larynx (Ch. 5) · Combined Intensity Changes with Lung Pressure and F0 (Ch. 9) · Register Equalization with Laryngeal Adjustments and Lung Pressure (Ch. 10)

A component of a periodic sound whose frequency is a whole-number multiple of the fundamental. The glottal source produces harmonics at F₀, 2F₀, 3F₀ and so on.

Appears in: Sources of Sound (Ch. 5) · The Glottal Source Function (Ch. 5) · Secondary Sound Sources in the Larynx (Ch. 5) · Frequency Spectra & Spectral Slope (Ch. 5) · The Meaning of a Spectrum (Ch. 5) · The Spectral Slope (Ch. 5) and 68 more

The ratio of periodic (harmonic) energy to aperiodic (noise) energy in decibels. It remains informative in voices too irregular for period-based measures.

Also: HNR, harmonic-to-noise ratio, noise-to-harmonics ratio

Appears in: Some Definitions (Ch. 11) · Perturbations and Fluctuations (Ch. 11) · Periodicity and Modulation (Ch. 11) · Sources of Fluctuation and Perturbation (Ch. 11) · Signal Typing and Physical Measures (Ch. 11) · Signals with Small Perturbations (Ch. 11) and 18 more

The demonstration that sound speed depends on the medium: in a low-density gas the vocal tract resonances shift up while F₀ stays the same, transforming the timbre without changing pitch.

Appears in: Propagation Velocity (Ch. 5) · Wavelength (Ch. 5)

The statement that stress is directly proportional to strain, so a material returns to its original length when the load is removed. It describes linear elasticity, which vocal fold tissue only approximates at small strains.

Appears in: Elements of Continuum Mechanics (Ch. 2) · Stress and Strain (Ch. 2) · Constitutive Equations (Ch. 2) · A Mass-Spring Oscillator (Ch. 4) · Simple Harmonic Motion (Ch. 4)

A voice whose vocal fold length and vocal tract length point to different categories, for example long folds with a short neck (low pitch, bright timbre). Some operatic subcategories may arise this way.

Appears in: Vocal Tract Length (Ch. 7)

The U-shaped bone above the larynx that has no bony articulation with the skeleton. Suspended by muscles and ligaments, it supports the larynx and lets it move up and down.

Also: hyoid

Appears in: Hard-Tissue Morphology (Ch. 1) · Laryngeal Cartilages (Ch. 1) · The Hyoid Bone (Ch. 1) · Muscles of the Larynx (Ch. 1) · Extrinsic Muscles of the Larynx (Ch. 1) · Vascularity and Innervation of the Larynx (Ch. 1)

The difference between the loading and unloading paths on a stress–strain plot. The area inside the loop is energy dissipated as heat on every cycle of stretch and release.

Appears in: One-Dimensional Stress-Strain Relations in Vocal Fold Tissue (Ch. 2) · Hypothesis One: Subglottal Resonances (Ch. 10) · Sources of Fluctuation and Perturbation (Ch. 11) · Biomechanical Sources (Ch. 11) · Bifurcations and Chaos (Ch. 11)

The stress produced when the two vocal folds collide each cycle. From Newton's second law it scales with vibrational amplitude and frequency, which is why loud, high-pitched phonation carries the greatest risk of nodules.

Also: collision stress

Appears in: Stress and Strain (Ch. 2) · Time Dependence and Viscosity (Ch. 2) · An Application of Biomechanics to Vocal Nodules (Ch. 2) · Criteria for Oscillation (Ch. 4) · Time-Varying Glottal Pressure and Flow (Ch. 4) · Clinical and Pedagogical Issues (Oscillation) (Ch. 4) and 7 more

The property of keeping a nearly constant volume when deformed. Because vocal fold tissue is nearly incompressible, stretching a fold along its length makes it thinner.

Also: incompressible

Appears in: Elements of Continuum Mechanics (Ch. 2) · Stress and Strain (Ch. 2) · Conservation Laws for Flow in Ducts (Ch. 3) · Continuity Law of Incompressible Flow (Ch. 3) · Conservation of Energy (Bernoulli's Law) (Ch. 3) · Media Interfaces (Ch. 5)

Acoustic power per unit area, in watts per square meter. It is what a microphone senses and it falls with the square of distance from the source.

Appears in: Some Definitions of Terms (Ch. 9) · Radiation of Sound (Ch. 9) · Sound Intensity Level and Sound Pressure Level (Ch. 9) · Radiation from Simple Sources (Ch. 9) · Radiation from the Mouth (Ch. 9) · Variation of Intensity with Adduction, Lung Pressure, and F₀ (Ch. 9) and 75 more

The transverse and oblique muscles running between the two arytenoids. They draw the arytenoid bodies together, closing the posterior (cartilaginous) glottis.

Also: interarytenoid muscle, interarytenoid, IA

Appears in: Muscles of the Larynx (Ch. 1) · Intrinsic Muscles of the Larynx (Ch. 1) · Vascularity and Innervation of the Larynx (Ch. 1) · Muscle Fiber Typing (Ch. 2) · Criteria for Oscillation (Ch. 4) · Muscle Strength (Ch. 7) and 5 more

Muscles between the ribs. The external intercostals raise the rib cage for inspiration; the internal intercostals lower it and assist expiration during speech.

Also: intercostal muscle, intercostals

Appears in: Lung (Alveolar) Pressure (Ch. 3) · The Physical Process of Breathing (Boyle's Law) (Ch. 3) · Clinical and Pedagogical Notes on Breathing (Ch. 3) · Why Teach Breathing? (Ch. 3) · What Is the Proper Way to Support? (Ch. 3) · Sources of Fluctuation and Perturbation (Ch. 11) and 3 more

A technique that removes the vocal tract resonances and radiation effect from the recorded sound or oral airflow to recover the glottal flow waveform.

Also: inverse filter

Appears in: Sources of Sound (Ch. 5) · The Spectral Slope (Ch. 5) · Time-Varying Glottal Pressure and Flow (Ch. 4) · Frequency Spectrum of the Resonating Tube (Ch. 6) · Filters and Filtering (Ch. 6) · The Amplitude-to-Length Ratio (Ch. 8) and 11 more

Because radiated power spreads over a sphere whose area grows with the square of the radius, intensity falls to one quarter when distance doubles, a drop of 6 dB.

Appears in: Some Definitions of Terms (Ch. 9) · Radiation of Sound (Ch. 9) · Sources of Sound (Ch. 5)

A muscle contraction in which overall length stays constant while internal force rises. In the larynx it allows vocal fold stiffness to change without a change in length.

Appears in: A Brief Introduction to Muscles (Ch. 2) · Vocal Fold Stiffness and Mass (Ch. 8) · Muscle Activation Plot for the Body-Cover Model (Ch. 8)

Changing cricothyroid and thyroarytenoid activity together so that vocal fold length stays constant while tension changes. It moves along a constant-length line on the muscle activation plot.

Appears in: Mechanics of Vocal Fold Elongation (Ch. 8)

Opening the jaw raises the first formant substantially while affecting the higher formants much less. It is the adjustment sopranos use to bring F₁ up to a high F₀.

Cycle-to-cycle variation in the fundamental period, expressed as an absolute time, as a percentage of the mean period, or as a smoothed quotient. Healthy voices typically stay below about 1 percent.

Also: frequency perturbation

Appears in: Some Definitions (Ch. 11) · Perturbations and Fluctuations (Ch. 11) · Variability (Ch. 11) · Jitter and Shimmer (Ch. 11) · Periodicity and Modulation (Ch. 11) · Sources of Fluctuation and Perturbation (Ch. 11) and 22 more

The layered connective tissue between the epithelium and the thyroarytenoid muscle: a loose superficial layer (Reinke's space), an elastin-rich intermediate layer, and a collagen-rich deep layer.

Appears in: Morphology of Vocal Fold Soft Tissue (Ch. 1) · Vascularity and Innervation of the Larynx (Ch. 1) · Subdivisions of Mechanics (Ch. 2) · Fundamentals of Tissue Viscoelasticity (Ch. 2) · One-Dimensional Stress-Strain Relations in Vocal Fold Tissue (Ch. 2) · Criteria for Oscillation (Ch. 4) and 14 more

Smooth, layered flow in which fluid particles follow parallel paths. It produces no noise and occurs at low Reynolds numbers.

Also: laminar

Appears in: Flow Resistance (Glottal Resistance) (Ch. 3) · Subdivisions of Mechanics (Ch. 2) · Vowel Shapes (Ch. 6) · Power Losses (Ch. 9) · Sources of Fluctuation and Perturbation (Ch. 11) · Biomechanical Sources (Ch. 11) and 1 more

An adductor that pulls the muscular process forward and downward, rotating the vocal processes toward the midline to close the membranous glottis.

Also: lateral cricoarytenoid, LCA

Appears in: Laryngeal Cartilages (Ch. 1) · Muscles of the Larynx (Ch. 1) · Intrinsic Muscles of the Larynx (Ch. 1) · Vascularity and Innervation of the Larynx (Ch. 1) · Muscle Fiber Typing (Ch. 2) · Criteria for Oscillation (Ch. 4) and 5 more

All formant frequencies fall in proportion as the vocal tract lengthens, for example by lowering the larynx or protruding the lips. A ten percent longer tract lowers every formant by roughly ten percent.

A pedagogical term for a favorable larynx–vocal tract interaction that lightens the load on the folds at certain pitches, as if the voice were lifted.

Appears in: Epilogue (Ch. 10) · The Physical Process of Breathing (Boyle's Law) (Ch. 3) · Conservation of Energy (Bernoulli's Law) (Ch. 3)

Rounding or protruding the lips lowers all formants; spreading the lips raises them. It is one of the quickest ways to darken or brighten a vowel.

The involuntary increase in vocal intensity, with added high-frequency emphasis, when speaking in noise. It contributes to occupational voice overuse.

Appears in: Clinical and Pedagogical Issues (Intensity) (Ch. 9) · Use of Intensity Variation in Speech and Song (Ch. 9) · Intensity Versus Intelligibility (Ch. 9) · The Hazards of Pressed Voice (Ch. 9)

The spectrum averaged over a long passage containing many vowels, which converges to a signature of vocal tract length. Cleveland used its peak frequency to separate basses, baritones and tenors.

Also: LTAS, long-term average spectrum

Appears in: Vocal Tract Length (Ch. 7) · Clinical and Pedagogical Issues (Classification) (Ch. 7) · Summary of Classification Methods (Ch. 7) · Frequency Spectra & Spectral Slope (Ch. 5) · The Meaning of a Spectrum (Ch. 5) · The Spectral Slope (Ch. 5) and 6 more

A perceptual quantity that exists only in an auditory system. Because the ear is most sensitive between about 1 and 3 kHz, sounds of equal energy are not equally loud.

Appears in: Some Definitions of Terms (Ch. 9) · Radiation of Sound (Ch. 9) · Sound Intensity Level and Sound Pressure Level (Ch. 9) · Radiation from the Mouth (Ch. 9) · Variation of Intensity with Adduction, Lung Pressure, and F₀ (Ch. 9) · Variation of Intensity with Vocal Tract Adjustments (Ch. 9) and 54 more

The greatest stress a fully activated muscle can generate, about 100 kPa for canine thyroarytenoid. Its ratio to passive stress decides how much influence thyroarytenoid activity has on F₀.

Appears in: The Body-Cover Model of F₀ Control (Ch. 8) · Active Tissue in Vibration (Ch. 8) · Active Stress of Muscles (Ch. 2) · Involuntary Register Transitions: Two Hypotheses (Ch. 10) · Hypothesis Two: Maximum Active Thyroarytenoid Stress (Ch. 10)

The steepest negative slope of the glottal flow waveform, reached at closure. Larger values add high-frequency energy and are the main determinant of vocal intensity at the source.

Also: MFDR

Appears in: The Glottal Source Function (Ch. 5) · Variation of Intensity with Adduction, Lung Pressure, and F₀ (Ch. 9) · Glottal Source Power and Inverse Filtering (Ch. 9) · Dependence of Glottal Source Power on Adduction (Ch. 9) · Vocal Efficiency (Ch. 9) · Problems with Glottal Efficiency Definitions and Calculations (Ch. 9) and 1 more

The proposal that modal register ends when the thyroarytenoid reaches its maximum active stress, about 100 kPa, which the string equation places near 500 Hz for a 10 mm fold.

The anterior, vibrating portion of the glottis, bounded by the soft tissue of the vocal folds from the anterior commissure to the vocal processes. Its length is the main determinant of fundamental frequency.

The length of the vibrating portion of the fold, from the anterior commissure to the vocal process. It, rather than body size or total laryngeal size, is the primary determinant of average fundamental frequency.

Also: membranous length

Appears in: Classification Based on Size (Ch. 7) · Fundamental Frequency and Vocal Fold Length (Ch. 7) · Critical Periods of Vocal Change (Ch. 7) · Childhood (Ch. 7) · Adolescence (Ch. 7) · The Physiologic Absurdity of Choir Arrangements (Ch. 7) and 6 more

A sustained note that swells from soft to loud and back. It trains the coordination of adduction and thyroarytenoid activity with lung pressure so the register does not change with loudness.

Appears in: The Modal-Falsetto Transition (Ch. 10) · Clinical and Pedagogical Issues (Ch. 10) · Register Equalization with Laryngeal Adjustments and Lung Pressure (Ch. 10) · Clinical and Pedagogical Issues (Intensity) (Ch. 9) · Use of Intensity Variation in Speech and Song (Ch. 9) · Cultured (Artistic) Fluctuations (Ch. 11) and 1 more

A production with spectral slope between chest and falsetto and amplitude close to chest voice. It bridges chest to falsetto without an audible break.

Also: middle voice, mixed voice, head voice

Appears in: Temporal Gap and Spectral Slope (Ch. 10) · The Modal-Falsetto Transition (Ch. 10) · Hypothesis One: Subglottal Resonances (Ch. 10) · Hypothesis Two: Maximum Active Thyroarytenoid Stress (Ch. 10) · Clinical and Pedagogical Issues (Ch. 10) · Register Equalization with Laryngeal Adjustments and Lung Pressure (Ch. 10) and 17 more

The register of ordinary speech, with firm closure, a shallow spectral slope and full involvement of the vocal fold body. It corresponds roughly to chest voice in singing.

Also: chest register, chest voice, modal voice

Appears in: Perception of Vocal Registers (Ch. 10) · Temporal Gap and Spectral Slope (Ch. 10) · The Pulse-Modal Transition (Ch. 10) · The Modal-Falsetto Transition (Ch. 10) · Involuntary Register Transitions: Two Hypotheses (Ch. 10) · Hypothesis Two: Maximum Active Thyroarytenoid Stress (Ch. 10) and 38 more

The wave that travels upward and outward across the surface of the vocal fold cover during each cycle, produced by the vertical phase difference between lower and upper margins.

Appears in: Vocal Tract Inertance: The One-Mass Model (Ch. 4) · Nonuniform Tissue Movement: Multimass Models (Ch. 4) · Normal Modes of Vibration in Vocal Fold Tissues (Ch. 4) · Clinical and Pedagogical Issues (Oscillation) (Ch. 4) · Maintaining Adequate Hydration (Ch. 4) · Morphology of Vocal Fold Soft Tissue (Ch. 1) and 26 more

A graph with normalized thyroarytenoid activity on one axis and cricothyroid activity on the other. Lines of constant fold length (or constant F₀) show which muscle combinations produce which result.

Appears in: Mechanics of Vocal Fold Elongation (Ch. 8) · Muscle Activation Plot for the Body-Cover Model (Ch. 8) · Involuntary Register Transitions: Two Hypotheses (Ch. 10)

The lateral projection of each arytenoid cartilage. The lateral cricoarytenoid pulls it forward to adduct the folds; the posterior cricoarytenoid pulls it backward to abduct them.

Appears in: Hard-Tissue Morphology (Ch. 1) · Laryngeal Cartilages (Ch. 1) · Intrinsic Muscles of the Larynx (Ch. 1)

The frequency at which a system oscillates freely once disturbed, set by the square root of its stiffness divided by its mass.

Appears in: Simple Oscillators (Ch. 4) · Criteria for Oscillation (Ch. 4) · Types of Oscillation (Ch. 4) · The Swing as a Simple Oscillator (Ch. 4) · A Mass-Spring Oscillator (Ch. 4) · Oscillators All Around Us (Ch. 4) and 6 more

The vowel produced by a uniform tube (as in schwa). For a 17.5 cm male tract the formants fall near 500, 1500 and 2500 Hz, the odd quarter-wave resonances.

Also: schwa

Appears in: Articulatory and Acoustic Descriptions of Vowels (Ch. 6) · A Three-Tube Approximation (Ch. 6) · Filters and Filtering (Ch. 6) · Wave Interference and Standing Waves (Ch. 5) · Summary of Classification Methods (Ch. 7) · Register Equalization by Vocal Tract Adjustments (Ch. 10)

A node is a point in a standing wave where a quantity (pressure or velocity) stays at zero; an antinode is where it swings to its maximum. Pressure nodes coincide with velocity antinodes.

Also: antinode

Appears in: Wavelength (Ch. 5) · Wave Interference and Standing Waves (Ch. 5) · Reflection Coefficients (Ch. 6) · Frequency Spectrum of the Resonating Tube (Ch. 6) · Aerodynamic Sources (Ch. 11)

Stiffness that rises progressively with elongation, giving a stress–strain curve that bends upward. It lets the vocal fold sustain large tension at high pitch and is required for elongation to raise pitch at all.

Also: nonlinear elastic

Appears in: Stress and Strain (Ch. 2) · Constitutive Equations (Ch. 2) · One-Dimensional Stress-Strain Relations in Vocal Fold Tissue (Ch. 2) · Active Stress of Muscles (Ch. 2)

A natural pattern of vibration in which every part of a structure moves at the same frequency with a fixed spatial shape. Complex motion can be described as a sum of normal modes.

Also: eigenmode

Appears in: Simple Harmonic Motion (Ch. 4) · Normal Modes of Vibration in Vocal Fold Tissues (Ch. 4) · Clinical and Pedagogical Issues (Oscillation) (Ch. 4) · Use of the Silent-H or Sigh for Voice Onset and Release (Ch. 4) · Quarter-Wave Resonance (Ch. 6)

A simplified representation of each vocal fold as a single mass on a spring. It oscillates only with help from vocal tract inertance because it has no vertical phase difference of its own.

Appears in: Mechanisms for Self-Sustained Vocal Fold Oscillation (Ch. 4) · Vocal Tract Inertance: The One-Mass Model (Ch. 4)

The fraction of each cycle during which the glottis is open. Values around 0.4 to 0.7 are typical; higher values go with breathy voice and lower values with pressed voice.

Also: OQ

Appears in: Sources of Sound (Ch. 5) · The Glottal Source Function (Ch. 5) · Frequency Spectra & Spectral Slope (Ch. 5) · The Meaning of a Spectrum (Ch. 5) · The Spectral Slope (Ch. 5) · Some Instrumentation for Clinical Use (Ch. 4) and 8 more

Maximum acoustic power occurs at an open quotient of about 0.5 to 0.6, slightly to the breathy side of normal, not with maximally pressed phonation.

The pitch region at which phonation is most efficient for an individual, judged by low threshold pressure, good glottal efficiency and stable vibration rather than by any fixed fraction of the range.

Also: optimal pitch

Appears in: Clinical and Pedagogical Issues (F0) (Ch. 8) · Finding the Best Speaking Pitch (Ch. 8) · Warm-up Exercises (Ch. 8)

Repetitive back-and-forth motion about an equilibrium position, driven by a restoring force. A mass on a spring is the simplest example; the vocal folds are a far more complex one.

Appears in: Classical Description of Vocal Fold Oscillation (Ch. 4) · Simple Oscillators (Ch. 4) · Criteria for Oscillation (Ch. 4) · Types of Oscillation (Ch. 4) · The Swing as a Simple Oscillator (Ch. 4) · A Mass-Spring Oscillator (Ch. 4) and 81 more

The gradual conversion of laryngeal cartilage to bone, beginning in the third decade and completing in the eighth. Partial ossification may support fold tension; excessive ossification limits joint movement.

Appears in: Critical Periods of Vocal Change (Ch. 7) · Maturity and Advanced Age (Ch. 7) · Hard-Tissue Morphology (Ch. 1) · Finding the Best Speaking Pitch (Ch. 8) · Limitations in F0 Range (Ch. 8)

The two parts of the cricothyroid muscle. The more vertical pars recta mainly rotates the cricothyroid joint; the more horizontal pars obliqua mainly slides the cartilages, adding further elongation.

Also: pars recta, pars obliqua

Appears in: Mechanics of Vocal Fold Elongation (Ch. 8) · Intrinsic Muscles of the Larynx (Ch. 1)

In an enclosed fluid at rest, an applied pressure is transmitted rapidly and equally throughout. It is why the alveolar airspace can be treated as having a single lung pressure.

Appears in: Fluid Pressure (Ch. 3) · Pascal's Law (Ch. 3) · Lung (Alveolar) Pressure (Ch. 3) · Thoracic, Pleural, and Abdominal Pressure (Ch. 3)

An involuntary register transition found consistently at a particular pitch, in the region of 300 to 350 Hz for both sexes: the primo passaggio of females and the secondo passaggio of males.

Also: passaggi

Appears in: Temporal Gap and Spectral Slope (Ch. 10) · The Modal-Falsetto Transition (Ch. 10) · Involuntary Register Transitions: Two Hypotheses (Ch. 10) · Hypothesis One: Subglottal Resonances (Ch. 10) · Hypothesis Two: Maximum Active Thyroarytenoid Stress (Ch. 10) · Register Equalization with Laryngeal Adjustments and Lung Pressure (Ch. 10) and 9 more

The connective-tissue sheath that wraps a fascicle (bundle) of muscle fibers. The whole muscle is wrapped in epimysium and each fiber in endomysium.

Appears in: A Brief Introduction to Muscles (Ch. 2) · Active Stress of Muscles (Ch. 2)

The time taken for one complete cycle of vibration, the reciprocal of frequency. A 200 Hz tone has a period of 5 milliseconds.

Appears in: The Glottal Source Function (Ch. 5) · Frequency Spectra & Spectral Slope (Ch. 5) · The Meaning of a Spectrum (Ch. 5) · The Spectral Slope (Ch. 5) · Sinusoidal Waves (Ch. 5) · Wavelength (Ch. 5) and 61 more

An oscillation that repeats only every two cycles because even and odd cycles differ, producing a subharmonic at half the fundamental. It usually arises from left–right asymmetry.

Also: period-doubling

Appears in: Signals with Small Perturbations (Ch. 11) · Bifurcations and Chaos (Ch. 11) · Periodicity (Ch. 4) · Frequency Spectra & Spectral Slope (Ch. 5) · The Meaning of a Spectrum (Ch. 5) · The Pulse-Modal Transition (Ch. 10)

Cycle-to-cycle irregularity in fundamental period or amplitude, occurring on the time scale of a single glottal cycle. Jitter and shimmer are its two classic measures.

Appears in: Some Definitions (Ch. 11) · Perturbations and Fluctuations (Ch. 11) · Variability (Ch. 11) · Jitter and Shimmer (Ch. 11) · Periodicity and Modulation (Ch. 11) · Sources of Fluctuation and Perturbation (Ch. 11) and 27 more

In Chapter 4: The minimum lung pressure needed to start and sustain vocal fold oscillation, typically a few hundred pascals. It rises with tissue stiffness, viscosity, fundamental frequency and glottal gap.

In Chapter 9 (and pitch): The minimum lung pressure for oscillation, about 0.2 kPa near speaking pitch and rising roughly quadratically above it. It sets the soft limit of the voice range profile.

Also: PTP

Appears in: Criteria for Oscillation (Ch. 4) · Types of Oscillation (Ch. 4) · The Swing as a Simple Oscillator (Ch. 4) · Simple Harmonic Motion (Ch. 4) · Vocal Tract Inertance: The One-Mass Model (Ch. 4) · Time-Varying Glottal Pressure and Flow (Ch. 4) and 23 more

A jitter measure that compares each period with a five-period local average, giving even stronger resistance to slow fluctuations. Its amplitude counterpart is the amplitude perturbation quotient.

Also: PPQ

Appears in: Some Definitions (Ch. 11) · Jitter and Shimmer (Ch. 11) · Sources of Fluctuation and Perturbation (Ch. 11) · Signal Typing and Physical Measures (Ch. 11) · Signals with Small Perturbations (Ch. 11)

The pressure in the thin fluid-filled space between the lungs and the chest wall. It is normally below atmospheric, holding the lungs expanded against their own recoil.

Appears in: Pascal's Law (Ch. 3) · Lung (Alveolar) Pressure (Ch. 3) · Thoracic, Pleural, and Abdominal Pressure (Ch. 3) · Measurement of Lung Pressure (Ch. 3)

The only abductor of the vocal folds. It pulls the muscular process backward, rotating the arytenoids so the vocal processes swing apart and the glottis opens for breathing.

Also: posterior cricoarytenoid, PCA

Appears in: Laryngeal Cartilages (Ch. 1) · Muscles of the Larynx (Ch. 1) · Intrinsic Muscles of the Larynx (Ch. 1) · Vascularity and Innervation of the Larynx (Ch. 1) · Muscle Fiber Typing (Ch. 2) · The F1-F2 Vowel Chart (Ch. 6) and 3 more

Phonation with excessive medial compression: low open quotient, restricted flow, sharp closure that sounds loud, and high collision forces that raise the risk of nodules and other trauma.

Also: pressed phonation

Appears in: Variation of Intensity with Adduction, Lung Pressure, and F₀ (Ch. 9) · Glottal Source Power and Inverse Filtering (Ch. 9) · Dependence of Glottal Source Power on Adduction (Ch. 9) · Phonation Threshold Pressure (Ch. 9) · Dependence of Glottal Source Power on Lung Pressure and F0 (Ch. 9) · Combined Intensity Changes with Lung Pressure and F0 (Ch. 9) and 21 more

Force per unit area exerted by a fluid, measured in pascals or centimeters of water. One kilopascal is about ten centimeters of water; conversational lung pressure is roughly half to one kilopascal.

Appears in: Fluid Pressure (Ch. 3) · Pascal's Law (Ch. 3) · Lung (Alveolar) Pressure (Ch. 3) · Thoracic, Pleural, and Abdominal Pressure (Ch. 3) · Measurement of Lung Pressure (Ch. 3) · The Pulmonary System (Ch. 3) and 132 more

The rise in F₀ produced by an increase in lung pressure, a few hertz per centimeter of water, larger for lax folds than for stiff ones. It couples pitch to loudness unless the larynx compensates.

Appears in: Dependence of Glottal Source Power on Lung Pressure and F0 (Ch. 9)

The speed at which a sound disturbance travels through a medium, set by the medium's stiffness and density: about 343 m/s in air at room temperature and about 350 m/s in the warm vocal tract.

Appears in: Propagation of Sound (Ch. 5) · Propagation Velocity (Ch. 5) · The Space-Time Concept of a Wave (Ch. 5) · Sinusoidal Waves (Ch. 5) · Wavelength (Ch. 5) · Wave Impedance (Ch. 5) and 3 more

The pubertal transformation of the voice. In males the membranous fold length grows about 60 percent and F₀ drops roughly an octave; the thyroarytenoid enlarges and the glottis becomes more rectangular.

Appears in: Limitations in F0 Range (Ch. 8)

The lowest register, also called vocal fry, produced below about 70 Hz. Each glottal pulse is heard as a separate burst followed by a gap, giving a popping or crackling quality.

Also: vocal fry, fry register

Appears in: Perception of Vocal Registers (Ch. 10) · Temporal Gap and Spectral Slope (Ch. 10) · The Pulse-Modal Transition (Ch. 10) · Clinical and Pedagogical Issues (Ch. 10) · Epilogue (Ch. 10) · Register Terminology (Ch. 10) and 16 more

A stair-step change in perceived quality that occurs while the underlying physiologic or acoustic variable changes continuously. The transitions, not the plateaus, define registers.

A tube closed at one end and open at the other, like the vocal tract closed at the glottis. It resonates when its length is an odd number of quarter wavelengths, giving formants at c/4L, 3c/4L, 5c/4L.

Also: quarter-wavelength resonator, quarter wave resonator

Appears in: Quarter-Wave Resonance (Ch. 6) · Half-Wave Resonance (Ch. 6) · Articulatory and Acoustic Descriptions of Vowels (Ch. 6) · Hypothesis One: Subglottal Resonances (Ch. 10)

The effect of sound leaving the mouth into open air, which boosts the spectrum by about 6 dB per octave and partly offsets the falling slope of the glottal source.

Appears in: Frequency Spectrum of the Resonating Tube (Ch. 6) · Sources of Sound (Ch. 5) · The Meaning of a Spectrum (Ch. 5) · The Spectral Slope (Ch. 5) · Radiation of Sound (Ch. 9) · Radiation from Simple Sources (Ch. 9) and 5 more

At low frequencies the mouth radiates almost uniformly in all forward directions; above a few hundred hertz radiation becomes increasingly directional, up to 10 to 15 dB stronger straight ahead at high frequencies.

Also: mouth radiation, lip radiation

Appears in: Radiation of Sound (Ch. 9) · Radiation from Simple Sources (Ch. 9) · Radiation from the Mouth (Ch. 9) · The Spectral Slope (Ch. 5) · Wavelength (Ch. 5) · Reflection Coefficients (Ch. 6) and 1 more

The branch of the vagus nerve that supplies every intrinsic laryngeal muscle except the cricothyroid. Its long looping course (around the aortic arch on the left) makes it vulnerable to injury.

Also: RLN

Appears in: Laryngeal Cartilages (Ch. 1) · Muscles of the Larynx (Ch. 1) · Intrinsic Muscles of the Larynx (Ch. 1) · Vascularity and Innervation of the Larynx (Ch. 1) · Descriptive Overview of F₀ Control (Ch. 8) · Active Tissue in Vibration (Ch. 8) and 1 more

The fraction of an incident pressure wave that is reflected at an interface, (z₂ − z₁)/(z₂ + z₁). It is +1 at a rigid wall, −1 at an open end into a vacuum, and 0 when impedances match.

Appears in: Wave Impedance (Ch. 5) · Reflection Coefficients (Ch. 5) · Wave Interference and Standing Waves (Ch. 5) · Sound Propagation in Tubes (Ch. 6) · Acoustic Impedance and Reflection (Ch. 6) · Reflection Coefficients (Ch. 6) and 4 more

A jitter measure that compares each period with the average of itself and its two neighbors, reducing sensitivity to slow pitch changes such as vibrato.

Also: RAP

Appears in: Some Definitions (Ch. 11) · Jitter and Shimmer (Ch. 11) · Sources of Fluctuation and Perturbation (Ch. 11) · Signal Typing and Physical Measures (Ch. 11) · Signals with Small Perturbations (Ch. 11)

The air that remains in the lungs after the most complete exhalation possible. It cannot be used for speech.

Appears in: Lung Volume (Ch. 3)

A dimensionless ratio of inertial to viscous forces in a flow. Low values give laminar flow and high values turbulent flow.

Appears in: Conservation Laws for Flow in Ducts (Ch. 3) · Conservation of Energy (Bernoulli's Law) (Ch. 3) · Flow Resistance (Glottal Resistance) (Ch. 3) · Sources of Fluctuation and Perturbation (Ch. 11) · Aerodynamic Sources (Ch. 11)

The repeating contractile unit of a muscle fiber, bounded by Z-discs, in which thin actin filaments slide past thick myosin filaments to shorten the muscle.

Appears in: A Brief Introduction to Muscles (Ch. 2) · Active Stress of Muscles (Ch. 2) · Hypothesis Two: Maximum Active Thyroarytenoid Stress (Ch. 10)

The proportional difference in a critical dimension between instruments of a family. Orchestral families use about 4:1; adult human vocal folds differ by only about 1.6:1, so voice types cannot be spread four octaves apart.

Appears in: Clinical and Pedagogical Issues (Classification) (Ch. 7) · The Physiologic Absurdity of Choir Arrangements (Ch. 7)

Oscillation maintained by a steady energy source rather than by a periodic driving force. The vocal folds convert the steady flow of air into oscillatory motion, like a flag flapping in a constant wind.

Also: self-sustaining oscillation

Appears in: Classical Description of Vocal Fold Oscillation (Ch. 4) · Simple Oscillators (Ch. 4) · Criteria for Oscillation (Ch. 4) · Types of Oscillation (Ch. 4) · The Swing as a Simple Oscillator (Ch. 4) · Oscillators All Around Us (Ch. 4) and 7 more

Partially closing the tract at the lips, as in straw phonation or lip trills. Supraglottal pressure rises, transglottal pressure and collision forces fall, and phonation threshold pressure drops.

Also: SOVT, semi-occluded vocal tract exercises, straw phonation

Appears in: Dependence of Glottal Source Power on Adduction (Ch. 9) · Phonation Threshold Pressure (Ch. 9) · Dependence of Glottal Source Power on Lung Pressure and F0 (Ch. 9) · Vocal Tract Transfer Gain (Ch. 9) · Formant Tuning (Ch. 9) · Combined Intensity Changes with Lung Pressure and F0 (Ch. 9) and 10 more

Cycle-to-cycle variation in peak amplitude, expressed in decibels or as a percentage. Healthy voices typically stay below about 3 percent.

Also: amplitude perturbation

Appears in: Some Definitions (Ch. 11) · Perturbations and Fluctuations (Ch. 11) · Variability (Ch. 11) · Jitter and Shimmer (Ch. 11) · Periodicity and Modulation (Ch. 11) · Sources of Fluctuation and Perturbation (Ch. 11) and 21 more

Titze's classification: Type 1 nearly periodic (perturbation measures valid); Type 2 with subharmonics or strong modulation; Type 3 with no apparent periodic structure; Type 4 aphonic noise.

Also: signal typing, type 1 signal, type 2 signal, type 3 signal, type 4 signal

Appears in: Perturbations and Fluctuations (Ch. 11) · Jitter and Shimmer (Ch. 11) · Signal Typing and Physical Measures (Ch. 11) · Signals with Small Perturbations (Ch. 11) · Nonstationarity and Trends (Ch. 11) · Bifurcations and Chaos (Ch. 11) and 3 more

Beginning phonation with the folds slightly separated so airflow builds gradually and a stable mode establishes at low amplitude before adduction and amplitude increase.

Sinusoidal oscillation produced by a restoring force proportional to displacement. It is the basic building block for describing periodic motion.

Appears in: Simple Oscillators (Ch. 4) · Criteria for Oscillation (Ch. 4) · The Swing as a Simple Oscillator (Ch. 4) · Graphical and Mathematical Representations of Oscillatory Movement (Ch. 4) · Periodicity (Ch. 4) · Simple Harmonic Motion (Ch. 4) and 1 more

A prominent peak near 2.5 to 3 kHz in trained classical voices, produced when a narrowed epilarynx above a lowered larynx and wide pharynx clusters the third, fourth and fifth formants. It lets a voice carry over an orchestra.

Also: singer's formant cluster, singing formant

Appears in: Variation of Intensity with Vocal Tract Adjustments (Ch. 9) · Vocal Tract Transfer Gain (Ch. 9) · Formant Tuning (Ch. 9) · Vocal Ring (the Singer's Formant) (Ch. 9) · Vocal Efficiency (Ch. 9) · Glottal Efficiency (Ch. 9) and 7 more

The ratio of the opening time to the closing time of the glottal flow pulse. A large value means an abrupt closure, which strengthens the upper harmonics.

Appears in: The Glottal Source Function (Ch. 5) · Glottal Source Power and Inverse Filtering (Ch. 9)

The explanation of muscle contraction in which cross-bridges on myosin attach to actin, pull, detach and reattach, sliding the filaments past each other without either filament changing length.

Appears in: A Brief Introduction to Muscles (Ch. 2)

A propagating disturbance of pressure and particle motion in an elastic medium. In air it travels as alternating compressions and rarefactions.

Appears in: Sound Generation (Ch. 5) · Sources of Sound (Ch. 5) · The Glottal Source Function (Ch. 5) · Secondary Sound Sources in the Larynx (Ch. 5) · Frequency Spectra & Spectral Slope (Ch. 5) · The Meaning of a Spectrum (Ch. 5) and 106 more

Twenty times the logarithm of the ratio of a sound pressure to the reference pressure of 20 micropascals, in decibels. Doubling the pressure adds 6 dB; doubling the intensity adds 3 dB.

Also: SPL

Appears in: Some Definitions of Terms (Ch. 9) · Radiation of Sound (Ch. 9) · Sound Intensity Level and Sound Pressure Level (Ch. 9) · Radiation from Simple Sources (Ch. 9) · Variation of Intensity with Adduction, Lung Pressure, and F₀ (Ch. 9) · Vocal Tract Transfer Gain (Ch. 9) and 13 more

The model of vowel production in which the glottal source spectrum is multiplied by the vocal tract's frequency response (filter) and the radiation characteristic. The source sets the harmonics; the tract sets the envelope.

Also: source-filter model

Appears in: Frequency Spectrum of the Resonating Tube (Ch. 6) · Articulatory and Acoustic Descriptions of Vowels (Ch. 6) · The F1-F2 Vowel Chart (Ch. 6) · Vowel Shapes (Ch. 6) · Filters and Filtering (Ch. 6) · Clinical and Pedagogical Issues (Vowels) (Ch. 6) and 12 more

As a classifier: The average pitch of neutral speech, typically four to five semitones above the bottom of the voice range profile. On its own it is a hazardous basis for classification because it never tests the full range of muscle contraction.

Also: SFF, speaking F₀, speaking F0

Appears in: Fundamental Frequency and Vocal Fold Length (Ch. 7) · Muscle Strength (Ch. 7) · Childhood (Ch. 7) · Maturity and Advanced Age (Ch. 7) · Clinical and Pedagogical Issues (Classification) (Ch. 7) · The Physiologic Absurdity of Choir Arrangements (Ch. 7) and 5 more

F₁ and F₂ moving toward each other, produced by a pharyngeal constriction as in [a]. The opposite, spectral diffusion, occurs with an oral constriction as in [i].

Appears in: Two-Tube Approximations of the Vocal Tract (Ch. 6) · Clinical and Pedagogical Issues (Vowels) (Ch. 6) · Rules for Modifying Vowels (Ch. 6)

The rate at which harmonic amplitudes fall with frequency, in decibels per octave. Modal voice rolls off at roughly −12 dB per octave; abrupt closure makes the slope shallower and breathy voice makes it steeper.

Appears in: Sources of Sound (Ch. 5) · The Glottal Source Function (Ch. 5) · Frequency Spectra & Spectral Slope (Ch. 5) · The Meaning of a Spectrum (Ch. 5) · The Spectral Slope (Ch. 5) · Frequency Spectrum of the Resonating Tube (Ch. 6) and 16 more

A register change perceived because the harmonic roll-off changes abruptly, from brassy to fluty, driven by a change in vocal fold adduction at the lower margin.

Appears in: Perception of Vocal Registers (Ch. 10) · Temporal Gap and Spectral Slope (Ch. 10) · Clinical and Pedagogical Issues (Ch. 10) · Epilogue (Ch. 10)

A display of frequency against time with intensity as darkness or color. A wideband analysis shows formants as dark bands; a narrowband analysis resolves individual harmonics.

Appears in: The F1-F2 Vowel Chart (Ch. 6) · Spectral Analysis of Vowels (Ch. 6) · The Sound Spectrograph (Ch. 6) · Frequency Spectra & Spectral Slope (Ch. 5) · Vocal Ring (the Singer's Formant) (Ch. 9) · Temporal Gap and Spectral Slope (Ch. 10) and 5 more

The distribution of a sound's energy across frequency. A periodic voice source has a line spectrum of harmonics; noise has a continuous spectrum.

Appears in: Sources of Sound (Ch. 5) · The Glottal Source Function (Ch. 5) · Secondary Sound Sources in the Larynx (Ch. 5) · Frequency Spectra & Spectral Slope (Ch. 5) · The Meaning of a Spectrum (Ch. 5) · The Spectral Slope (Ch. 5) and 46 more

Because F₀ depends on the square root of stiffness over mass, a fourfold change in effective stiffness changes F₀ by one octave. A two-octave range needs a sixteenfold stiffness variation.

The stationary pattern of nodes and antinodes formed when a wave and its reflection interfere in a tube or on a string. Resonances of the vocal tract are standing waves.

Appears in: Wavelength (Ch. 5) · Wave Impedance (Ch. 5) · Wave Interference and Standing Waves (Ch. 5) · Sound Propagation in Tubes (Ch. 6) · Acoustic Impedance and Reflection (Ch. 6) · Reflection Coefficients (Ch. 6) and 8 more

The assumption that a signal's mean and variability do not drift over the analysis window. Onset and offset transients, pitch glides and voice breaks violate it and should be excluded or detrended.

Also: nonstationarity

Appears in: Perturbations and Fluctuations (Ch. 11) · Variability (Ch. 11) · Periodicity and Modulation (Ch. 11) · Signal Typing and Physical Measures (Ch. 11) · Signals with Small Perturbations (Ch. 11) · Nonstationarity and Trends (Ch. 11) and 2 more

The fractional deformation of a material: change in length divided by original length. It is dimensionless and is often given as a percentage.

Appears in: What is Biomechanics? (Ch. 2) · The Mechanical System (Ch. 2) · Elements of Continuum Mechanics (Ch. 2) · Stress and Strain (Ch. 2) · Constitutive Equations (Ch. 2) · Time Dependence and Viscosity (Ch. 2) and 50 more

Force per unit area acting on a material, measured in pascals. Tensile stress pulls a tissue apart, compressive stress squeezes it, and shear stress slides one layer over another.

Appears in: Materials for Sound Production (Ch. 2) · What is Biomechanics? (Ch. 2) · Review of Basic Mechanics (Ch. 2) · Subdivisions of Mechanics (Ch. 2) · The Mechanical System (Ch. 2) · Elements of Continuum Mechanics (Ch. 2) and 58 more

The gradual decline of stress in a tissue held at a constant length after being stretched. Vocal fold tissue shows a steep drop in the first second followed by a slower decay.

Appears in: Elements of Continuum Mechanics (Ch. 2) · Time Dependence and Viscosity (Ch. 2) · Fundamentals of Tissue Viscoelasticity (Ch. 2) · One-Dimensional Stress-Strain Relations in Vocal Fold Tissue (Ch. 2) · Biomechanical Sources (Ch. 11)

Sensory endings that signal changes in vocal fold or cricothyroid length. Together with auditory, pressure and joint receptors they feed back to the nervous system's control of F₀.

Also: stretch receptor

Appears in: Descriptive Overview of F₀ Control (Ch. 8) · Involvement of the Nervous System (Ch. 8)

F₀ = (1/2L)√(σ/ρ): fundamental frequency rises with the square root of longitudinal stress, falls with the square root of density, and is inversely proportional to vibrating length.

Also: string equation

Appears in: Analogies with Vibrating Strings and Ribbons (Ch. 8) · Quantitative F₀ Analysis for the Cover Model (Ch. 8)

The proposal that involuntary register breaks occur where subglottal formant pressure opposes vocal fold motion, predicting favorable zones near 146 and 306 Hz and unfavorable zones near 204 and 510 Hz.

Appears in: Involuntary Register Transitions: Two Hypotheses (Ch. 10) · Hypothesis One: Subglottal Resonances (Ch. 10) · Hypothesis Two: Maximum Active Thyroarytenoid Stress (Ch. 10)

A spectral component at an integer fraction of the fundamental (F₀/2, F₀/3 …). It appears when the vibratory pattern repeats over more than one glottal cycle.

Appears in: Perturbations and Fluctuations (Ch. 11) · Jitter and Shimmer (Ch. 11) · Signal Typing and Physical Measures (Ch. 11) · Signals with Small Perturbations (Ch. 11) · Nonstationarity and Trends (Ch. 11) · Bifurcations and Chaos (Ch. 11) and 8 more

The vagus branch whose external branch supplies the cricothyroid muscle and whose internal branch provides sensation to the larynx above the vocal folds.

Also: SLN

Appears in: Muscles of the Larynx (Ch. 1) · Intrinsic Muscles of the Larynx (Ch. 1) · Vascularity and Innervation of the Larynx (Ch. 1) · Descriptive Overview of F₀ Control (Ch. 8) · Limitations in F0 Range (Ch. 8) · Phonation Threshold Pressure (Ch. 9) and 1 more

A register change perceived because the glottal period becomes longer than the formant decay time plus a detectable gap, so continuous sound becomes a series of pulses.

Appears in: Perception of Vocal Registers (Ch. 10) · Temporal Gap and Spectral Slope (Ch. 10) · Epilogue (Ch. 10)

The average pitch region in which a song or role predominantly lies, as distinct from its extreme notes. A high tessitura demands sustained laryngeal muscle contraction.

Appears in: Classification Based on Secondary Factors (Ch. 7) · Muscle Strength (Ch. 7) · Musicianship (Ch. 7) · Occupation and Marketability (Ch. 7) · Adolescence (Ch. 7) · Clinical and Pedagogical Issues (Classification) (Ch. 7) and 3 more

The pattern of muscle use that keeps lung pressure steady over a long phrase: braking recoil with inspiratory muscles at high volume, adding internal intercostal activity at mid volume, and adding abdominal compression at low volume.

Also: three phases of expiration

The intrinsic muscle that forms the body of the vocal fold, running from the thyroid cartilage to the arytenoid. Contraction shortens and thickens the fold and stiffens its body.

Also: thyroarytenoid, TA

Appears in: Laryngeal Cartilages (Ch. 1) · Muscles of the Larynx (Ch. 1) · Intrinsic Muscles of the Larynx (Ch. 1) · Morphology of Vocal Fold Soft Tissue (Ch. 1) · Vascularity and Innervation of the Larynx (Ch. 1) · One-Dimensional Stress-Strain Relations in Vocal Fold Tissue (Ch. 2) and 48 more

The large shield-shaped cartilage that forms the front and sides of the larynx. The vocal folds attach to its inner surface near the anterior commissure, and its prominence is the Adam's apple.

Appears in: Some Anatomical Terminology (Ch. 1) · Hard-Tissue Morphology (Ch. 1) · Laryngeal Cartilages (Ch. 1) · The Hyoid Bone (Ch. 1) · Intrinsic Muscles of the Larynx (Ch. 1) · Extrinsic Muscles of the Larynx (Ch. 1) and 10 more

The volume of air moved in and out during one cycle of quiet breathing, about half a liter at rest.

Appears in: Lung Volume (Ch. 3) · Airflow in Speech and Nonspeech (Ch. 3) · Sources of Fluctuation and Perturbation (Ch. 11)

The mechanical advantage of the cricothyroid over the thyroarytenoid: maximum force times lever arm for one divided by the same product for the other. It sets the slope of the isometric lines.

Appears in: Mechanics of Vocal Fold Elongation (Ch. 8)

An involuntary, usually irregular rhythmic modulation of the voice, roughly 3 to 8 Hz, arising from neurological conditions such as essential tremor or Parkinson's disease, or from respiratory instability.

Also: vocal tremor

Appears in: Some Definitions (Ch. 11) · Perturbations and Fluctuations (Ch. 11) · Variability (Ch. 11) · Jitter and Shimmer (Ch. 11) · Periodicity and Modulation (Ch. 11) · Sources of Fluctuation and Perturbation (Ch. 11) and 16 more

A rapid alternation between two distinct pitches, about 10 to 15 Hz, requiring precise cricothyroid oscillation. Lip and tongue trills, by contrast, are aerodynamic oscillations used as semi-occluded exercises.

Appears in: Cultured (Artistic) Fluctuations (Ch. 11) · Vibrato (Ch. 11) · Trill (Ch. 11) · Trillo (Ch. 11) · Types of Oscillation (Ch. 4) · Vocal Tract Inertance: The One-Mass Model (Ch. 4) and 5 more

A Baroque ornament of rapid amplitude pulsation on a single pitch at about 6 to 8 Hz, distinct from vibrato (pitch modulation) and trill (pitch alternation).

Appears in: Trillo (Ch. 11)

Chaotic flow with eddies and vortices that arises above a critical Reynolds number, as in the glottis at high flow. It generates aspiration noise.

Also: turbulence

Appears in: Pulmonary Power (Ch. 3) · Conservation Laws for Flow in Ducts (Ch. 3) · Continuity Law of Incompressible Flow (Ch. 3) · Conservation of Energy (Bernoulli's Law) (Ch. 3) · Flow Resistance (Glottal Resistance) (Ch. 3) · Criteria for Oscillation (Ch. 4) and 19 more

A model with an upper and a lower mass per fold coupled by a spring. It reproduces the vertical phase difference and can oscillate without a vocal tract.

Appears in: A Mass-Spring Oscillator (Ch. 4) · Vocal Tract Inertance: The One-Mass Model (Ch. 4) · Nonuniform Tissue Movement: Multimass Models (Ch. 4) · Normal Modes of Vibration in Vocal Fold Tissues (Ch. 4) · Bifurcations and Chaos (Ch. 11)

An approximation of the vocal tract as a back tube (pharynx) and a front tube (mouth) of different areas. A narrow pharynx with a wide mouth gives an [a]-like pattern; a wide pharynx with a narrow mouth gives an [i]-like pattern.

Appears in: Vowel Shapes (Ch. 6) · Two-Tube Approximations of the Vocal Tract (Ch. 6) · A Three-Tube Approximation (Ch. 6)

The time lag between the motion of the lower and upper edges of the vocal fold, with the bottom leading the top. It creates the alternation of convergent and divergent shapes that transfers energy from airflow to tissue.

Appears in: Vocal Tract Inertance: The One-Mass Model (Ch. 4) · Nonuniform Tissue Movement: Multimass Models (Ch. 4) · Normal Modes of Vibration in Vocal Fold Tissues (Ch. 4) · Some Instrumentation for Clinical Use (Ch. 4) · Free-Body Diagrams (Ch. 2) · The Mechanical System (Ch. 2) and 10 more

A voluntary, regular modulation of F₀ (with accompanying amplitude modulation) at about 5 to 7 Hz and roughly ±50 to 100 cents, cultivated in Western classical singing.

Appears in: Some Definitions (Ch. 11) · Perturbations and Fluctuations (Ch. 11) · Variability (Ch. 11) · Jitter and Shimmer (Ch. 11) · Periodicity and Modulation (Ch. 11) · Cultured (Artistic) Fluctuations (Ch. 11) and 11 more

Rate is the number of modulation cycles per second; extent is the peak deviation of pitch in cents. Rates outside about 5 to 8 Hz and extents beyond about ±100 cents are judged unattractive.

Also: vibrato rate, vibrato extent

Appears in: Perturbations and Fluctuations (Ch. 11) · Cultured (Artistic) Fluctuations (Ch. 11) · Vibrato (Ch. 11) · Nonstationarity and Trends (Ch. 11) · Clinical and Pedagogical Issues (Perturbations) (Ch. 11)

The combination of elastic (spring-like, energy-storing) and viscous (dashpot-like, energy-dissipating) behavior that characterizes biological soft tissue, making its response depend on the rate of loading.

Also: viscoelastic

Appears in: What is Biomechanics? (Ch. 2) · The Mechanical System (Ch. 2) · Elements of Continuum Mechanics (Ch. 2) · Stress and Strain (Ch. 2) · Constitutive Equations (Ch. 2) · Time Dependence and Viscosity (Ch. 2) and 11 more

A material's resistance to flow: the ratio of stress to the rate of strain. Higher viscosity means slower deformation for a given stress and more energy lost as heat during vibration.

Appears in: Elements of Continuum Mechanics (Ch. 2) · Time Dependence and Viscosity (Ch. 2) · Morphology of Vocal Fold Soft Tissue (Ch. 1) · Flow Resistance (Glottal Resistance) (Ch. 3) · Classical Description of Vocal Fold Oscillation (Ch. 4) · Simple Oscillators (Ch. 4) and 22 more

The maximum volume of air that can be exhaled after a maximal inhalation, typically about four to five liters in adults. Conversational speech uses only a small fraction of it.

Appears in: Lung Volume (Ch. 3) · Airflow in Speech and Nonspeech (Ch. 3) · Pulmonary Power (Ch. 3) · Why Teach Breathing? (Ch. 3) · Critical Periods of Vocal Change (Ch. 7) · Childhood (Ch. 7) and 4 more

In Chapter 1: The intermediate and deep layers of the lamina propria together: a dense band of elastin and collagen fibers running the length of the fold that bears longitudinal tension at high pitch.

In Chapter 8 (in pitch control): The layer that bears most of the longitudinal stress at high F₀ so the mucosa can stay loose and keep its mucosal wave. Canine folds lack it and top out near 220 Hz in excised experiments.

Appears in: Hard-Tissue Morphology (Ch. 1) · Laryngeal Cartilages (Ch. 1) · Intrinsic Muscles of the Larynx (Ch. 1) · Morphology of Vocal Fold Soft Tissue (Ch. 1) · Biological Factors Influencing Stiffness (Ch. 8) · The Cover Model of F₀ Control (Ch. 8) and 14 more

The anterior projection of each arytenoid cartilage to which the posterior end of the vocal fold attaches. The gap between the two vocal processes sets the pre-phonatory glottal width.

Appears in: Laryngeal Cartilages (Ch. 1) · Intrinsic Muscles of the Larynx (Ch. 1) · Morphology of Vocal Fold Soft Tissue (Ch. 1) · Clinical and Pedagogical Issues (Oscillation) (Ch. 4) · Use of the Silent-H or Sigh for Voice Onset and Release (Ch. 4) · The Glottal Source Function (Ch. 5) and 6 more

A perceptually distinct region of vocal quality that can be maintained over some range of pitch and loudness, separated from other regions by an abrupt (quantal) change in quality.

Also: register

Appears in: Perception of Vocal Registers (Ch. 10) · Temporal Gap and Spectral Slope (Ch. 10) · The Pulse-Modal Transition (Ch. 10) · The Modal-Falsetto Transition (Ch. 10) · Involuntary Register Transitions: Two Hypotheses (Ch. 10) · Hypothesis One: Subglottal Resonances (Ch. 10) and 53 more

The sluggishness of the air column above the glottis. As glottal flow accelerates, supraglottal pressure rises and pushes the folds apart; as flow decelerates, pressure falls and pulls them together, adding energy in phase with tissue velocity.

Also: inertance

Appears in: Classical Description of Vocal Fold Oscillation (Ch. 4) · Types of Oscillation (Ch. 4) · The Swing as a Simple Oscillator (Ch. 4) · A Mass-Spring Oscillator (Ch. 4) · Simple Harmonic Motion (Ch. 4) · Mechanisms for Self-Sustained Vocal Fold Oscillation (Ch. 4) and 10 more

The increase in radiated power the vocal tract gives a harmonic that lies near a formant, potentially tens of decibels, without any extra aerodynamic power.

Appears in: Vocal Tract Transfer Gain (Ch. 9)

Assigning a voice to a category such as soprano, alto, tenor or bass on the basis of range, timbre and physiology, while also weighing secondary factors such as muscle strength, musicianship, culture and career.

Appears in: Classification Based on Size (Ch. 7) · Fundamental Frequency and Vocal Fold Length (Ch. 7) · Vocal Tract Length (Ch. 7) · Classification Based on Secondary Factors (Ch. 7) · Muscle Strength (Ch. 7) · Musicianship (Ch. 7) and 14 more

In Chapter 7: A plot of the softest and loudest sound pressure level a singer can produce at each fundamental frequency across the whole range, also called a phonetogram. Ideal classification places the voice near its center.

In Chapter 9 (in intensity control): The phonetogram's lower contour rises steeply with pitch because threshold pressure rises, so the dynamic range is widest in mid range and narrowest at the extremes.

Also: VRP, phonetogram

Appears in: Muscle Strength (Ch. 7) · Clinical and Pedagogical Issues (Classification) (Ch. 7) · Summary of Classification Methods (Ch. 7) · Variation of Intensity with Adduction, Lung Pressure, and F₀ (Ch. 9) · The Voice Range Profile (Ch. 9) · Problems with Glottal Efficiency Definitions and Calculations (Ch. 9) and 7 more

An everyday word for the amount of sound with no formal scientific definition. Dynamic markings on a score are a relative guide of the same kind.

Appears in: Some Definitions of Terms (Ch. 9) · Radiation from Simple Sources (Ch. 9) · Radiation from the Mouth (Ch. 9) · Variation of Intensity with Adduction, Lung Pressure, and F₀ (Ch. 9) · Glottal Source Power and Inverse Filtering (Ch. 9) · Dependence of Glottal Source Power on Adduction (Ch. 9) and 46 more

The sensation of where a vowel is 'placed', which the chapter links to acoustic pressure being highest at a constriction. Because acoustic pressure rises in narrow regions, the focus is felt at the narrowing, not the widening.

Appears in: Clinical and Pedagogical Issues (Vowels) (Ch. 6) · Sensations of Acoustic Pressures: Vowel Focus (Ch. 6)

Deliberately altering a vowel's articulation, usually in the upper singing range, to move a formant toward a harmonic. It trades some intelligibility for intensity and ease.

Appears in: Reflection Coefficients (Ch. 6) · Frequency Spectrum of the Resonating Tube (Ch. 6) · The F1-F2 Vowel Chart (Ch. 6) · Vowel Shapes (Ch. 6) · A Three-Tube Approximation (Ch. 6) · Spectral Analysis of Vowels (Ch. 6) and 19 more

The ratio of acoustic pressure to particle velocity in a medium, equal to density times sound speed. Mismatched impedances at a boundary cause reflection.

Appears in: Propagation of Sound (Ch. 5) · Wave Impedance (Ch. 5) · Reflection of Sound (Ch. 5) · Reflection Coefficients (Ch. 5) · Sound Propagation in Tubes (Ch. 6)

The distance between successive compressions of a sound wave, equal to propagation velocity divided by frequency. A 100 Hz tone in air has a wavelength of about 3.4 meters.

Appears in: Sources of Sound (Ch. 5) · The Spectral Slope (Ch. 5) · Propagation Velocity (Ch. 5) · Sinusoidal Waves (Ch. 5) · Wavelength (Ch. 5) · Media Interfaces (Ch. 5) and 14 more

Problematic vibrato variants: a wobble is too slow and too wide, a bleat (or tremolo) too fast. Both signal loss of the regular, controlled modulation of good vibrato.

Also: wobble, bleat

Appears in: Cultured (Artistic) Fluctuations (Ch. 11) · Vibrato (Ch. 11) · Trillo (Ch. 11) · Clinical and Pedagogical Issues (Perturbations) (Ch. 11)

The ratio of stress to strain for a linearly elastic material, a measure of stiffness. Vocal fold tissue has no single value because its stiffness rises with elongation.

Appears in: Constitutive Equations (Ch. 2) · Dependence of Glottal Source Power on Adduction (Ch. 9) · Phonation Threshold Pressure (Ch. 9) · Hypothesis Two: Maximum Active Thyroarytenoid Stress (Ch. 10)