1. science

Phonation
SPPA 4030 Speech Science
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Topic Sequence
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Anatomy review
Achieving phonation
Capturing glottal and vocal fold behavior
Phonatory control parameters
Lifecourse considerations
Clinical considerations
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Topic Sequence
• Anatomy review
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The hyo-laryngeal complex
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Extrinsic/Supplementary Muscles
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Intrinsic muscles
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Muscular Actions
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CA joint function
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Muscular actions on vocal folds
• Alter position
– Adduction
• LCA, IA, TA
– Abduction
• PCA
• Alter tension (and length)
– Increase/decrease longitudinal tension
• Balance between TA and CT
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Extrinsic/supplementary muscles
• Holds the larynx in the neck
• Allows positional change of the larynx
– Elevates when swallowing
– Elevates during certain speech activities
• Elevating pitch
• High vowel production
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The larynx
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“Layered” structure of vocal fold
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Basic Structure of the vocal fold
epithelium
connective tissue
superficial layer
tissue loosely connected to the other layers
Lamina
propria
intermediate layer
elastic fibers
Vocal ligament
deep layer
collagen fibers (not stretchy)
muscle (TA)
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Topic Sequence
• Anatomy review
• Achieving phonation
– Features of the mucosal wave
– Two-mass model of phonation
– More complex models of phonation
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Vocal fold vibration (mucosal wave)
Vertical phase difference
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2-mass model
Upper part of vocal fold
Mechanical coupling stiffness
Lower part of vocal fold
Coupling between
mucosa & muscle
TA muscle
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Myoelastic aerodynamic theory of
phonation
Necessary & sufficient conditions for phonation
1. Adduction
2. Longitudinal tension
3. Aerodynamic pressures
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•VF adducted & tensed → myoelastic pressure (Pme )
•Glottis is closed
•subglottal air pressure (Psg) ↑
•Psg ~ 8-10 cm H20, Psg > Pme
•L and R M1 separate
•Transglottal airflow (Utg) = 0
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As M1 separates, M2 follows due to
mechanical coupling stiffness
Psg > Pme
glottis begins to open
Psg > Patm therefore Utg > 0
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Utg ↑ ↑ since glottal aperature << tracheal circumference
Utg ↑ Ptg ↓ due to Bernoulli effect
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Bernoulli’s law
P + ½  U2 = K
where
P = air pressure
 = air density
U = air velocity
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Utg ↑ Ptg ↓ due to Bernoulli effect
Ptg < Pme
M1 returns to midline
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M2 follows M1 due to
mechanical coupling stiffness
‘other’ aerodynamic effects
Utg = 0
Pattern repeats 100-200 times a second
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Limitations of this simple model
• Actual VF movement is more complex
• Vocal folds have length and vary in
biomechanical properties along their
length
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Added features of vocal fold vibration
(mucosal wave)
Longitudinal phase difference
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Topic Sequence
• Anatomy review
• Achieving phonation
• Capturing glottal and vocal fold behavior
– Flow glottogram
– Electroglottogram
– Photoglottogram
– Visualization: stroboscopy & high speed
– Acoustic waveform analysis
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Topic Sequence
• Anatomy review
• Achieving phonation
• Capturing glottal and vocal fold behavior
– Photoglottogram
– Visualization: stroboscopy & high speed
– Flow glottogram
– Electroglottogram
– Acoustic waveform analysis
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Estimating glottal area
• Photoglottography (PGG)
• Videolaryngoscopy
– Stroboscopy
– High speed video
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illumination
Photoglottography (PGG)
Time
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Glottal area waveform
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Estimating degree of VF contact
• Electroglottography (EGG)
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Electroglottography (EGG)
• Human tissue =  conductor
• Air:  conductor
• Electrodes placed on each side of
thyroid lamina a high frequency, low
current signal is passed between them
• VF contact  =  impedance
• VF contact  =  impedance
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illumination
PGG
1/impedance
EGG
Time
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Estimating airflow (volume velocity)
• Flow glottogram
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1/impedance
illumination
PGG
EGG
Time
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Glottal airflow
Consequence of this vibration
• Air disturbance is caused by the “slapping”
together of the vocal folds
• Sound energy is maximum at glottic
closure
• Given the complexity of the vibratory
patterns of the vocal fold, the sound
produced at the glottis is complex and
periodic.
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Glottal waveform (Time domain)
• ‘triangular’ shaped
• Looks simple, but is complex
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Glottal waveform (Frequency domain)
• 12 dB/octave roll off
• Octave: doubling of frequency
• Harmonics: integer multiples of the fundamental
frequency (F0)
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Is this what we see coming from
the mouth?
• NO
• Glottal spectrum is shaped by the resonant
characteristics of the vocal tract
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Recall…
• Air disturbance is caused by the “slapping”
together of the vocal folds
• Sound energy is maximum at glottic
closure
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1/impedance
illumination
PGG
EGG
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Glottal airflow Sound pressure
Pressures needed to initiate
vibration
• Phonation threshold pressure
– Minimum pressure needed to set the vocal
folds into vibration
– 3-6 cm water
– ~3 for low Fo, 6 for higher Fo
– Higher for louder speech
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Topic Sequence
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•
•
•
Anatomy review
Achieving phonation
Capturing glottal and vocal fold behavior
Phonatory control parameters
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Fundamental frequency control
Amplitude control
Register control
Phonatory quality control
Phonation onset
Articulatory control
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Fundamental Frequency Control
• Fundamental frequency (Fo) = reflects rate
of vibratory cycle
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Fo Control
• Anatomical factors
Males ↑ VF mass and length = ↓ Fo
Females ↓ VF mass and length = ↑ Fo
• Subglottal pressure adjustment – show example
↑ Psg = ↑ Fo
• Laryngeal and vocal fold adjustments
↑ CT activity = ↑ Fo
TA activity = ↑ Fo or ↓ Fo
• Extralaryngeal adjustments
↑ height of larynx = ↑ Fo
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Fundamental Frequency
Average F0
• sustained vowels or spontaneous speech
• For “connected” speech, it is called speaking
fundamental frequency (SFF)
• Typical or ‘normative’ values depend on
gender and age
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Fundamental Frequency
Average F0
Infants
~350-500 Hz
Boys & girls (3-10) ~ 270-300 Hz
Young adult females
~ 220 Hz
Young adult males ~ 120 Hz
Older females
drops
Older males
increases
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F0 variability
• F0 varies due to
– syllabic stress
– emphatic stress
– grammatic and semantic factors
– Phonetics (in some languages)
• Provides a melody to speech (prosody)
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F0SD (Hz) or pitch sigma (semitones)
• reflects the spread of values around the
average F0
• May be measured in semitones (12
semitones = 1 octave) rather than Hz
• ~2-4 semitones for normal speakers
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F0 Range (in a speaking task)
• Maximum F0 - minimum F0
Infants
Boys & girls (3-10)
Young adult females
Young adult males
~1200 Hz
~ 150-200 Hz
~ 100 Hz
~ 60-70 Hz
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Maximum Phonational Frequency
Range
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Not measured during speech
highest possible F0 - lowest possible F0
measured in Hz, semitones or octaves
Males ~ 80-700 Hz
Females
~135-1000 Hz
3 octaves often considered normal
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Ways to measure fundamental
frequency
• Time domain vs. frequency domain
• Manual vs. automated measurement
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How do we measure Fo?
• Computer-based acoustic analysis
programs
– e.g. tf32!!, as well as many others
• Electronic equipment specially designed to
extract Fo and amplitude measure
– e.g. Kay Elemetrics Visipitch
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Topic Sequence
•
•
•
•
Anatomy review
Achieving phonation
Capturing glottal and vocal fold behavior
Phonatory control parameters
–
–
–
–
–
–
Fundamental frequency control
Amplitude control
Register control
Phonatory quality control
Phonation onset
Articulatory control
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Amplitude
• Measured as Pressure or Intensity
• Subglottal pressure adjustment
↑ Psg = ↑ sound pressure
• Laryngeal and vocal fold adjustments
↑ medial compression = ↑ sound pressure
• Supralaryngeal adjustments
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Average sound pressure level
conversation:~ 65-80 dB SPL
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Sound pressure variability
•  SPL to mark stress
• Adds to speech prosody
• Standard deviation for neutral reading
material: ~ 10 dB SPL
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Dynamic Range
• Amplitude analogue to maximum
phonational frequency range
• ~50 – 115 dB SPL
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How do we measure amplitude?
• Computer-based acoustic analysis programs
– e.g. tf32!!, as well as many others
• Electronic equipment specially designed to
extract Fo and amplitude measure
– e.g. Kay Elemetrics Visipitch
• Sound level meter (amplitude only)
• Old-fashioned equipment like an oscilloscope
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Combining F0 & Amplitude
Voice Range Profile
• Plots dynamic range as a function of
phonation range
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Voice Range Profile
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Topic Sequence
•
•
•
•
Anatomy review
Achieving phonation
Capturing glottal and vocal fold behavior
Phonatory control parameters
–
–
–
–
–
–
Fundamental frequency control
Amplitude control
Register control
Phonatory quality control
Phonation onset
Articulatory control
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Vocal Register
• Refers to a distinct mode of vibration
According to Hollien…
• Range of consecutive Fos produced with a
distinct voice quality
• Fo range should have minimal overlap with
other registers
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Vocal Register
• Pulse register (a.k.a. vocal fry, glottal fry,
creaky voice)
• Modal register (a.k.a. chest register)
• Falsetto register (a.k.a. loft register)
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Vocal Registers
Pulse (Glottal fry)
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30-80 Hz, mean ~ 60 Hz
Closed phase very long (90 % cycle)
May see biphasic pattern of vibration (open,
close a bit, open and close completely)
Low subglottal pressure (2 cm water)
Energy dies out over the course of a cycle so
parts of the cycle has very little energy
Hear each individual cycle
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Vocal Registers
Modal
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VF are relatively short and thick
Reduced VF stiffness
Large amplitude of vibration
Possesses a clear closed phase
The result is a voice that is relatively loud and
low in pitch
Average values cited refer to modal register
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Vocal Registers
Falsetto
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500-1100 Hz (275-600 Hz males)
VF are relatively long and thin
Increased VF stiffness
Small amplitude of vibration
Vibration less complex
Incomplete closure (no closed phase)
The result is a voice that is high in pitch
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Topic Sequence
•
•
•
•
Anatomy review
Achieving phonation
Capturing glottal and vocal fold behavior
Phonatory control parameters
–
–
–
–
–
–
Fundamental frequency control
Amplitude control
Register control
Phonatory quality control
Phonation onset
Articulatory control
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Vocal Quality
• Doesn’t have clear acoustic correlates like
pitch and loudness
• some acoustic measures that have
potential to be helpful in characterizing
voice qualities
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Voice Quality
Common Terms
• Breathiness
• Tense
• Roughness
• Strain
• Hoarseness
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Voice Quality
Auditory Perceptual Descriptors
• Breathiness
– Audible air escape in the voice
– Diminished or absent closed phase
– Correlated with
• high frequency noise
• sharper harmonic roll-off
• lower signal-to-noise ratio (SNR)
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Roll-off
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Signal (harmonic)-to-noise-ratio
(SNR or HNR)
• Glottal spectrum is not strictly periodic
• Periodic component
– Periodic cycling of vocal folds
• Noise component
– Aperiodicity in cycling
– Air “leakage” (Additive noise)
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Signal (harmonic)-to-noise-ratio
(SNR or HNR)
• ratio of signal amplitude to noise amplitude
•  SNR
– Relatively more signal
– Indicative of a normality
•  SNR
– Relatively more noise
– Indicative of disorder
• Normative values depend on method of
calculation
• “normal” SNR ~ 15
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Signal (harmonic)-to-noise-ratio
(SNR or HNR)
signal
Noise
‘floor’
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Signal (harmonic)-to-noise-ratio
(SNR or HNR)
signal
Noise
‘floor’
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Voice Quality
Auditory Perceptual Descriptors
• Tense or Pressed
– Perceptually contrasted with breathiness
– Correlated
• longer closed phase
• Less harmonic roll off
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Roll-off
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Voice Quality
Auditory Perceptual Descriptors
• Roughness
– Perceived cycle-to-cycle variability in voice
– Correlated with jitter (frequency perturbation)
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Cycle to cycle variability in
vibration
• Vocal fold vibration not strictly periodic
• ↓ frequency and amplitude fluctuations are
normal
• When variability is excessive, it sounds
abnormal
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Frequency variability
• Variability in the period of each successive
cycle of vibration
• Termed frequency perturbation or jitter
…
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Amplitude variability
• Variability in the amplitude of each
successive cycle of vibration
• Termed amplitude perturbation or
shimmer
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Sources of jitter and shimmer
• Small structural asymmetries of the L and
R vocal fold
• “material” on the vocal folds (e.g. mucus)
• Biomechanical events, such as
raising/lowering the larynx in the neck
• Small variations in tracheal pressures
• “Bodily” events – system noise
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Measuring jitter and shimmer
• No standard measurement approach
• Variability in how measures are is
reported
Jitter: typically reported as %, but can
be msec
• Normal ~ 0.2 - 1%
Shimmer: can be % or dB
• Normal ~ 0.5 dB
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Jitter demo
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Topic Sequence
•
•
•
•
Anatomy review
Achieving phonation
Capturing glottal and vocal fold behavior
Phonatory control parameters
–
–
–
–
–
–
Fundamental frequency control
Amplitude control
Register control
Phonatory quality control
Phonation onset
Articulatory control
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Phonatory onset
• Timing of respiratory and phonatory
activities
– Simultaneous vocal attack
– Hard glottal attack
– Breathy attack
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Topic Sequence
•
•
•
•
Anatomy review
Achieving phonation
Capturing glottal and vocal fold behavior
Phonatory control parameters
–
–
–
–
–
–
Fundamental frequency control
Amplitude control
Register control
Phonatory quality control
Phonation onset
Articulatory control
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One other important role of
phonation
• ITS ABSENCE
• Many sounds are voiceless
• Laryngeal devoicing gesture
– Rapid abduction of vocal folds
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Clinical Considerations
• Abnormal voice: dysphonia
• Factors underlying dysphonia
– Disease to laryngeal tissue
– Neurologic and neuromuscular disease
– How the voice is used
– Muscle tension
– Psychological factors
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Clinical Considerations
• Can we phonate without our larynx?
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