Acoustics of Vowels

Question 1

Sound Source

Answer 1

Exhaled airstream can be used to provide two types of sound source

This sound is filtered by resonant frequencies of the vocal tract

Resonant frequencies are determined by the sizes and shapes in the vocal tract

Sizes and shapes in the vocal tract are determined by the movements and positions of the articulators – tongue, pharynx, palate, lips, jaw

Question 2

Resonance

Answer 2

Refers to the acoustic response of air molecules with the oral, nasal, and pharyngeal cavities to some source of sound that will set them into vibration.

Question 3

Articulatory Movements

Answer 3

Necessary for producing sounds in the vocal tract itself and for altering the acoustic resonance characteristics of the vocal tract depending on the various requirements for different speech sounds.

Question 4

Resonating Cavities

Answer 4

Include all of the air passages above the larynx from the glottis to the lips

(mouth, nose, and pharynx)

Question 5

Resonance Physiology

Answer 5

An air filled tube resonates at certain frequencies depending on

• Whether it is open at one end or both ends
• Its length
• Its shape
• The size of its openings

The larger the resonating chamber, the lower the frequency

The shapes and sizes of human vocal resonators can be varied by moving and positioning the articulators.

The sound source for vowels must be the vibrations of the vocal folds

Question 6

Pharynx

Answer 6

Tube of muscles in the posterior part of the vocal tract

The nasal, oral and laryngeal cavities open into the pharyngeal cavity

(throat)

Question 7

Styloglossus

Answer 7

Extrinsic muscle of the tongue

contraction pulls the tongue back and up

Question 8

Hypoglossus

Answer 8

Extrinsic muscle of the tongue

attached to the hyoid bone. Contraction results in tongue depression and backing

Question 9

Genioglossus

Answer 9

Extrinsic muscle of the tongue

contraction draws the hyoid bone and tongue root forward and results in a forward and upward movement of the tongue

Question 10

Intrinsic Tongue Muscles

Answer 10

Contained entirely within the tongue

Shape the tongue – especially its tip, into a variety of shapes, which contribute to vowel production

Superior longitudinal – curls the tongue tip up
Inferior longitudinal – depresses tongue tip

Question 11

Lip Muscles

Answer 11

orbicularis oris

risorius

Question 12

Acoustic Theory of Vowel Production (Gunnar Fant)

Answer 12

Based on three parameter that predict vocal tract resonances

The location of the main tongue constriction
The amount of lip protrusion
And vocal tract cross-sectional area

Question 13

Vocal Tract Resonance

Answer 13

Tubes (vocal tract) resonate naturally at certain frequencies that depend on the length and configuration of the tube

The vocal tract has soft absorbant walls

Never a constant cross-sectional area

Has a bend of 90 degrees where the oral cavity meets the pharynx

Question 14

Formants

Answer 14

Vocal tract resonances (distinctive energy regions)

R1 = F1 - lowest resonant frequency is most responsive to changes in mouth opening. Vowels with small mouth openings have low-frequency first formants.
R1/F1 = 500 Hz = most energy

R3 = F2 – most responsive to changes in the size of the oral cavity
R3/F2 = 1500 Hz

R5 = F3 – responsive to front versus back constriction
R5/F3 = 2500 Hz “singer’s formant”

First two formants determine what vowel sound is made

Standards against which to measure resonant frequencies

Question 15

Source and Filter

Answer 15

Energy source for all vowels is the vocal folds

This energy is shaped or filtered through the vocal tract

Any change in vocal tract configuration alters the frequencies at which the cavities resonate

As fundamental frequency changes the resonant formants do not change

Question 16

Formant Frequency

Answer 16

The frequency of the first formant is mostly determined by the height of the tongue body
High F1 = low vowel (low tongue body)
Low F1 = high vowel (high tongue body)

The frequency of the second formant is mostly determined by the frontness/backness of the tongue body
High F2 = front vowel
Low F2 = back vowel