1. Laryngeal Function and Speech Production

2. Learning Objectives
Describe the basic role of the larynx in speech and song.

3. What is the basic role of the larynx in speech and song
Sound source to excite the vocal tract
Voice
Whisper
Prosody
Fundamental frequency (F0) variation
Amplitude variation
Realization of phonetic goals
Voicing
Devoicing
Glottal frication (//, //)
Glottal stop (//)
Aspiration
Para-linguistic and extra-linguistic roles
Transmit affect
Speaker identity

4. Learning Objectives
Possess a knowledge of laryngeal anatomy sufficient to understand the biomechanics, aerodynamics and acoustics of phonation.

5. The hyo-laryngeal complex
SPPA 4030 Speech Science

6. Extrinsic/Supplementary Muscles
SPPA 4030 Speech Science

7. Intrinsic muscles
SPPA 4030 Speech Science

8. Muscular Actions
SPPA 4030 Speech Science

9. CA joint function
SPPA 4030 Speech Science

10. 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
SPPA 4030 Speech Science

11. 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
SPPA 4030 Speech Science

12. The larynx
SPPA 4030 Speech Science

13. “Layered” structure of vocal fold
SPPA 4030 Speech Science

14. Basic Structure of the vocal fold
epithelium
connective tissue
superficial layer
tissue loosely connected to the other layers
intermediate layer
elastic fibers
deep layer
collagen fibers (not stretchy)
muscle (TA)
Lamina
propria
Vocal ligament
SPPA 4030 Speech Science

15. The vocal fold through life…
Newborns
No layered structure of LP
LP loose and pliable
Children
Vocal ligament appears 1-4 yrs
3-layered LP is not clear until 15 yrs
Old age
Superficial layer becomes edematous & thicker
Thinning of intermediate layer and thickening of deep layer
Changes in LP more pronounced in men
Muscle atrophy

16. Learning Objectives
Describe the control variables of laryngeal function.

17. Laryngeal Opposing Pressure
Pressure that opposes translaryngeal air pressure
Sources
Muscular pressure
Surface tension
Gravity

18. Laryngeal Airway Resistance (LAR)
Components of LAR
Translaryngeal pressure
Translaryngeal flow
Values can vary widely
Resistance=Pressure/Flow

19. Glottal Size

20. Vocal Fold Stiffness

21. “Effective” Mass and Length

22. Learning Objectives
Outline and briefly describe the different types of sounds that can be produced by the larynx.

23. Laryngeal Sound Generation
Transient vs. Continuous
Glottal stops
Aperiodic vs. Periodic
Glottal fricatives
Whispering
Voice production/phonation

24. Laryngeal Sound Generation
Glottal stop
Glottal fricative

25. Learning Objectives Describe a single cycle of vocal fold oscillation
Describe why phonation is considered “quasi-periodic”
Describe the relationship between vocal fold motion (kinematics), laryngeal aerodynamics and sound pressure wave formation
Describe and draw idealized waveforms and spectra of the glottal sound source

26. Complexity of vocal fold vibration
Vertical phase difference
Longitudinal phase difference

27. The Glottal Cycle

28. Phonation is actually quasi-periodic
Complex Periodic
vocal fold oscillation
Aperiodic
Broad frequency noise embedded in signal
Non-periodic vocal fold oscillation
Asymmetry of vocal fold oscillation
Air turbulence

29. Flow Glottogram

30. Synchronous plots Sound pressure waveform (microphone at mouth)
Glottal Airflow
(inverse filtered mask signal)
Glottal Area
(photoglottogram)
Vocal Fold Contact
(electroglottogram)

31. Sound pressure wave
sound pressure
Instantaneous
Time

32. Learning Objectives
Explain vocal fold motion using the 2-mass model version of the myoelastic-aerodynamic theory of phonation

33. Glottal Aerodynamics: Some Terminology
Subglottal pressure
Translaryngeal Pressure (Driving Pressure)
Translaryngeal Airflow (Volume Velocity)
Laryngeal Airway Resistance
Phonation Threshold Pressure
Initiate phonation
Sustain phonation

34. Myoelastic Aerodynamic Theory of Phonation
Necessary and Sufficient Conditions
Vocal Folds are adducted (Adduction)
Vocal Folds are tensed (Longitudinal Tension)
Presence of Aerodynamic pressures (driving pressure)

35. 2-mass model Upper part of vocal fold Mechanical coupling stiffness
Lower part of vocal fold
Coupling between
mucosa & muscle
TA muscle

36. Definitions of terms
Pme : myoelastic pressure (aka laryngeal opposing pressure)
Psg : subglottal pressure
Patm: atmospheric pressure
Pwg : pressure within the glottis
Utg : transglottal (translaryngeal) airflow

37. 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
As M1 separates, M2 follows due to
mechanical coupling stiffness
Psg > Pme
glottis begins to open
Psg > Patm therefore Utg > 0

38. Utg ↑ ↑ since glottal aperature << tracheal circumference
Utg ↑ Pwg ↓ due to
Bernoulli effect
Pressure drop within the glottis
Bernoulli’s Law
P + ½ U2 = K
where
P = air pressure
 = air density
U = air velocity

39. Utg ↑ Pwg ↓ due to Bernoulli effect*
Pwg < Pme
M1 returns to midline
M2 follows M1 due to
mechanical coupling stiffness
Utg = 0
Pattern repeats times a second

40. Role of glottal shape
Current theories argue that Bernoulli effect plays a relatively small role in vocal fold closure.
More important is glottal shape. Pwg is lower for ‘divergent’ vs. ‘convergent’ shape.
As the glottis become divergent, Pwg drops resulting in the Pwg < Pme

42. Limitations of this simple model

43. Learning Objectives
Describe how speakers control fundamental frequency.
Provide expected values for different measures of fundamental frequency.
Describe different methods for measuring fundamental frequency.
Describe how speakers control sound pressure level.
Provide expected values for different measures of sound pressure level.

44. Quantifying frequency
Hertz: cycles per second (Hz)
Non-linear scales
Octave scale
1/3 octave bands
Semitones
Cents
Other “auditory scales”: e.g. mel scale

45. Fundamental Frequency (F0) Control
What factors dictate the vibratory frequency of the vocal folds?
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

46. Characterizing Fundamental Frequency (F0)
Average F0
speaking fundamental frequency (SFF)
Correlate of pitch
Infants
~ Hz
Boys & girls (3-10)
~ Hz
Young adult females
~ 220 Hz
Young adult males
~ 120 Hz
Older females: F0 ↓
Older males: F0 ↑
F0 variability
F0 varies due to
Syllabic & emphatic stress
Syntactic and semantic factors
Phonetics factors (in some languages)
Provides a melody (prosody)
Measures
F0 Standard deviation
~2-4 semitones for normal speakers
F0 Range
maximum F0 – minimum F0 within a speaking task

47. F0 in the first 10 years of life

48. F0 over the lifespan

49. Estimating the limits of vocal fold vibration
Maximum Phonational Frequency Range
highest possible F0 - lowest possible F0
Not a speech measure
measured in Hz, semitones or octaves
Males ~ Hz1
Females ~ Hz1
Around a 3 octave range is often considered “normal”
1Baken (1987)

50. Approaches to Measuring Fundamental Frequency (F0)
Time domain vs. frequency domain
Manual vs. automated measurement
Specific Approaches
Peak picking
Zero crossing
Autocorrelation
The cepstrum & cepstral analysis

51. Amplitude control during speech

52. Sound Pressure Level (SPL)
Average SPL
Correlate of loudness
conversation:
~ dBSPL
SPL Variability
 SPL to mark stress
Contributes to prosody
Measure
Standard deviation for neutral reading material:
~ 10 dBSPL

53. Estimating the limits of sound pressure generation
Dynamic Range
Amplitude analogue to maximum phonational frequency range
~50 – 115 dB SPL

54. Learning Objectives
Differentiate between different types of vocal attack.

56. Learning Objectives
Differentiate between different vocal registers.

57. 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
SPPA 4030 Speech Science

58. Vocal Register Modal register (a.k.a. chest register)
Pulse register (a.k.a. vocal fry, glottal fry, creaky voice)
Falsetto register (a.k.a. loft register)
SPPA 4030 Speech Science

59. Voice Registers

60. Vocal Registers Modal 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
SPPA 4030 Speech Science

61. Vocal Registers Pulse (Glottal fry) 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
SPPA 4030 Speech Science

62. Vocal Registers Falsetto 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
SPPA 4030 Speech Science

64. Learning Objectives
Describe the physiological and acoustic correlates of pressed, breathy and rough voice qualities.
Define terms such as harmonics (or signal) to noise ratio, jitter and shimmer.
Explain how physical description and quantification of the phonatory signal can be informative for clinical populations.

65. Vocal Quality no clear acoustic correlates like pitch and loudness
However, terms have invaded our vocabulary that suggest distinct categories of voice quality
Common Terms
Breathy
Tense/strained
Rough
Hoarse

66. Are there features in the acoustic signal that correlate with these quality descriptors?

67. Breathiness Perceptual Description Audible air escape in the voice
Physiologic Factors
Diminished or absent closed phase
Increased airflow
Potential Acoustic Consequences
Change in harmonic (periodic) energy
Sharper harmonic roll off
Change in aperiodic energy
Increased level of aperiodic energy (i.e. noise), particularly in the high frequencies

68. harmonics (signal)-to-noise-ratio (SNR/HNR)
harmonic/noise amplitude
 HNR
Relatively more signal
Indicative of a normality
 HNR
Relatively more noise
Indicative of disorder
Normative values depend on method of calculation
“normal” HNR ~ 15

69. Harmonic peak Noise ‘floor’ Harmonic peak Noise ‘floor’ Amplitude
Frequency

70. First harmonic amplitude
From Hillenbrand et al. (1996)

71. Spectral Tilt: Voice Source

72. Spectral Tilt: Radiated Sound

73. Tense/Pressed/Effortful/Strained Voice
Perceptual Description
Sense of effort in production
Physiologic Factors
Longer closed phase
Reduced airflow
Potential Acoustic consequences
Change in harmonic (periodic) energy
Flatter harmonic roll off

74. Spectral Tilt
Pressed
Breathy

75. Acoustic Basis of Vocal Effort
Perception of Effort
F0 + RMS + Open Quotient
Tasko, Parker & Hillenbrand (2008)

77. Roughness Perceptual Description Physiologic Factors
Perceived cycle-to-cycle variability in voice
Physiologic Factors
Vocal folds vibrate, but in an irregular way
Potential Acoustic Consequences
Cycle-to-cycle variations F0 and amplitude
Elevated jitter
Elevated shimmer

78. Period/frequency & amplitude variability
Jitter: variability in the period of each successive cycle of vibration
Shimmer: variability in the amplitude of each successive cycle of vibration …

79. Jitter and Shimmer Sources of jitter and shimmer
Small structural asymmetries of vocal folds
“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
Measuring jitter and shimmer
Variability in measurement approaches
Variability in how measures are reported
Jitter
Typically reported as % or msec
Normal ~ %
Shimmer
Can be % or dB
Norms not well established

80. Additional features of voice
Regular fluctuations in frequency (and amplitude)
Vocal tremor
Vocal “flutter”
Irregular fluctuations in frequency
Diplophonia and/or pitch breaks

81. Learning Objectives
Briefly describe range of instruments used to capture phonatory behavior including stroboscopy, photoglottography, electroglottography, and laryngeal aeroydynamics.

82. Measuring Glottal Behavior
Videolaryngoscopy
Stroboscopy
High speed video

83. Photoglottography (PGG)
illumination
Time

84. Electroglottography (EGG)
Human tissue =  conductor
Air:  conductor
Electrodes placed on each side of thyroid lamina
high frequency, low current signal is passed between them
VF contact  =  impedance
VF contact  =  impedance

85. Electroglottogram

86. Glottal Airflow
Instantaneous airflow is measured as it leaves the mouth
Looks similar to a pressure waveform
Can be inverse filtered to remove effects of vocal tract
Resultant is an estimate of the airflow at the glottis

87. Flow and Pressure Measurement

88. Flow and Pressure Measurement