CSD 353 Phonation

rigid

this type of laryngeal endoscope creates larger, more stable, brighter images, works only a sustained vowel. Client posture is unnatural. Ideal for close views of the VF or lesion, patients who can tolerate it, and when VF vibration patterns are important to observe when strobe light is used

vocal folds

layers of tissue stretched between the arytenoid cartilages and the thyroid cartilage of the larynx. They can be abducted or adducted, stretched out or compressed. They close medially, anterior to posterior. Should be open during breathing. Close for speech, subglottic pressure causes them to vibrate and create sound.

cover

the 2 most superficial layer of the vocal folds

squamous epithelium

most flexible layer of VF, very thin layer of skin cells

lamina propria

three layers of the VF which are still pretty flexible but progressively increasing stiffness by increasing the collogen

vocal ligament

another name for the intermediate and deep lamina propria. Also called the medial edge

body

The vocals muscle, thicker and denser than the other layers. the only layer with nerve innervation, provides stability.

neurochronaxic

this theory of VF movement is now defunct. It states that nerves innervate the vocal folds and cause them to vibrate at the desired frequency. But nerves can't fire fast enough

What is the myoelastic-aerodynamic theory?

It is a theory of vocal fold movement based on muscle elasticity and the laws of airflow.

What creates the repeated pattern of opening and closing in the vocal folds according to the myoelastic-aerodynamic theory?

A consistent stream of air flows past the vocal folds.

What factors interact in the myoelastic-aerodynamic theory?

The aerodynamic properties, subglottic pressure, and transglottal flow interact with the resistance and elasticity of the vocal fold tissues.

Closed Phase: Myoelastic-Aerodynamic Theory of Phonation

-Lateral Cricoarytenoids muscles

-Internal Arytenoids muscles

-Medial compression is created and holds the folds closed near midline.

- Subglottic pressure begins to increase as expiratory forces are met by the resistance from the adducted VF.

-In order for air to flow and set the VF into vibration, the subglottal pressure must be greater than the supraglottalpressure.

Opening Phase: Myoelastic-Aerodynamic Theory of Phonation

-As subglottic pressure builds, it becomes stronger than the resistance of the closed VF and forces them apart.

-Air wants to move to an area of lower pressure, so it moves upward through the glottis.

- The air sets the VF into vibration (like the tuning fork)

-This sound ("the glottal spectrum") is transmitted and thenmodified further through the vocal tract.

Closing Phase: Myoelastic-Aerodynamic Theory of Phonation

- Due to the elasticity of the VF, they begin to recoil back to midline.

- Respiratory drive is relatively constant so the same amount of air is going through a narrower constriction.

- As the glottis becomes more narrow, airflow increases and air pressure decreases.

- The decrease in air pressure also helps to close the VF.

Bernoulli Principle

An aerodynamic law stating that an increase in the velocity of air decreases air pressure

flow (positive) = pressure (negative)

voice and fundamental frequency

- During speech, the VF vibrate hundreds of times per second

-.The vibration creates a complex periodic sound wave.

-The rate at which the VF vibrate is the F0 and corresponds to the perceived pitch of voiced sounds.

-The rate of vibration depends on the length, mass, and tension of the VF.

- Changes in F0 is primarily determined by the tension of the Vocalis and contraction of the Cricothyroid muscle.

- So...the greater the mass and the less the tension, the slower the VF will vibrate.

PTP

this refers to the minimum amount of subglottic pressure to set the VF into motion. Varies with loudness and pitch.

- ranges from ~2-3 cm H20 for a soft voice

phonation threshold pressure

this is what PTP stands for

greater PTP when VF have more medial compression.

periodic

repeated pattern for sound waves where each period is one cycle of VF motion.

aperiodic

one reason why VF aren't pure-tones, a not perfecting repeating pattern

perturbation

one reason why VF aren't pure-tones, frequency and amplitude vary from cycle to cycle

harmonics

one reason why VF aren't pure-tones, they include other frequencies on top of the fundamental frequency, due to the vocal tract

frequency

average F0, frequency variability, frequency range, and jitter are all ways to measure this

intensity

average amplitude, amplitude variability, dynamic range, shimmer are all ways to measure this

noise

extra aperiodic sound

180-250 Hz

the range for average F0 for males

175-266 Hz

the range for average F0 for females

10-35 Hz

the range for SD frequency variability in conversation

< 3Hz

the range for SD frequency variability in a sustained vowel

80-700 Hz

this frequency range is generally expected for males

135-1100 Hz

this frequency range is generally expected for females

2.4

this is the average number of octaves a period

30-48 ST

this is a range of the average vocal range in semitones

<1%

the norm for jitter

Jitter

frequency perturbation

RAP = Relative Average Perturbation (3 cycles)

60-80 dB

the dB SPL norm range for average amplitude of typical voice

10-15 dB

the SD dB SPL norm range for amplitude variability

50-115 dB

the dB SPL norm range for dynamic range

<5%

the norm for shimmer

fundamental frequency

the rate at which the vocal folds are vibrating. There may be harmonics on top of it, but this is still the pitch that is heard

frequency range

this describes the max and minimum frequencies during a phonation sample

frequency variability

this describes SD of frequency changes over the course of a sample

How is loudness increased in voice production?

By increasing the amount of subglottal pressure.

What builds up subglottal pressure?

Increasing inspiratory capacity and medial compression of the vocal folds.

What happens to the vocal folds when subglottal pressure increases?

The folds are blown apart more forcefully and recoil with more force.

What effect does increased amplitude of vibration have on sound?

It generates a louder sound wave.

How does intensity relate to fundamental frequency?

Increases in intensity occur with increases in fundamental frequency.

semitones

these reflect the perceptual pitches that can be produced. Like notes, 12 in an octave

50-60 dB

dB SPL for "quiet" voice

105 dB

dB SPL for "loud" voice

vocal range profile

-Phonetogram

- Dynamic Range x Fundamental frequency (db SPL x F0)

- Sustained Vowel, loud/soft at different frequencies

- Upper Contour = Mac intensity

-Lower contour = min intensity. Each frequency attempted

Dervies: Min and max: frequency & amplitude Range: Frequency & Amplitude Average Amplitude

What does vocal quality refer to?

Voice = acoustics and quality.

What are the dimensions assessed in vocal quality?

Breathiness, Roughness, Pitch, Loudness, Resonance, Strain

How does vocal fold vibration affect vocal quality?

Quality is related to how the vocal folds vibrate (Hypoadduction / Hyperadduction).

What is velopharyngeal closure related to in vocal quality?

Resonance: Hyponasal / Hypernasal.

How is vocal quality measured perceptually?

Breathy, Rough, Pitch, Loudness, Strain, Weak Number and Categorical Rating scales.

hypoadduction

difficulty making the vocal folds close strongly enough or long enough for normal phonation that results in a weak, breathy voice that often deteriorates with increasing amounts of vocal use throughout the day

hyperadduction

Excessive movement toward the midline, often resulting in a tense voice quality.

hyponasal

reduced nasal resonance; sounds flat

Hypernasal

too much nasality

monotone

this is the layman term for low amplitude and frequency variability

intensity variability

the change in amplitude over time

dynamic range

the loudest and softest voices possible

variability

larger scale changes in frequency or amplitude over time

HNR

this ratio refers to the amount of aperiodic sound a speaker produces. High means a purer voice and low means lots of noise

register

portions of the total F0 range. Singers call them chest voice, head voice, and falsetto. Each one has a different manner of VF vibration. Transition is obvious with jitter/shimmer

pulse

this is low range of F0, 25-28 Hz. VF are short and thick, minimal tension, low PTP, incomplete closure. Cover: Lax, CT: relaxed. TA: contracted

modal

this is the typical range of F0, cover and body vibrates, more PTP than pulse

falsetto

this is very high F0. Less movement in body. VF are long, stiff, thin, edge is sharp. Superficial LP: lax, middle and deep LP: tense. VF don't completely close, highest PTP

electroglottograph

EGG - electrodes on the neck- measures impedance which corresponds with vocal fold contact

impedance

the difficulty of the electrical current to travel between the electrodes. There is higher during the open phase and less during the closed phase

Lx waveform

the output of the EGG

peak

the point of max closure, top of a waveform

trough

the bottom of the waveform, the point of most open VF

contact quotient

the duration of the closed phase divided by the period. The result is a percent of the cycle that the VF are closed. CQ increases with increased pitch

amplitude

on the Lx waveform this is measured in volts and represents the amount of closure/opening of VF

breathy

this kind of voice looks like a really long opening duration, low amplitude peak

hyperadduction

this kind of voice results in a long closing phase of the Lx waveform

pulse

modal

falsetto

laryngeal endoscopy

the method of viewing the VF where a probe with a camera and a light is sent down through the nose or mouth and you can see the VF on the screen

steady light

a steady halogen light is shined down on the VF, and you can see the tissue and muscular opening and closure. But the vibration of phonation is too fast to see.

stroboscopy

the flashing xenon light. Timing triggered by F0 of the voice as determined by a contact microphone or EGG

still

this type of stroboscopy is when the rate of flashing is locked, and you can see only one phase, because the light flashes at the same point of the vibration

flexible

this type of laryngeal endoscopy creates more natural productions but is more invasive. Subject to disruptive vertical movement, making it more difficult to achieve a stable image. May create a darker image. Ideal when the rigid is not possible, connected speech must be observed, vocal tract movements are important, velopharyngeal function is of interest

endoscopy

visual examination of a body cavity or canal using a specialized lighted instrument called an endoscope

jitter

frequency perturbation. Changes in frequency cycle to cycle

shimmer

amplitude perturbation. Changes in amplitude cycle to cycle

acoustic

these measures are objective, includes: frequency, intensity, perturbation, nasalance, HNR