Voice Production

Question 1

What is the vocal apparatus?

Answer 1

The set of organs that we use when we speak:
the lungs - generates air flow
the trachea
the larynx
the supra laryngeal vocal tract - the pharynx, the south and the nasal cavity

Question 2

What is the source filter theory?

Answer 2

Believes we have 2 functional components which are responsible for speech

Question 3

Source filter theory - stage 1

Answer 3

The source - a periodic wave is generated in the larynx (the source) by vibration of the vocal folds. The rate of vibration determines the fundamental frequency of the signals, affected the perceived pitch of the voice

Question 4

What does the rate of vibration in the larynx determine?

Answer 4

The fundamental frequency of signals, and the pitch
if high rate - high pitch
if low rate - low pitch

Question 5

Source filter theory - stage 2

Answer 5

The wave is filtered in the supra laryngeal cavities of the vocal tract (the filter), creating broad bands of energy called vocal tract resonances or formants - energy is distributed homogeneously - when we speak, changing shape of supra laryngeal

Question 6

What is the source?

Answer 6

The larynx

Question 7

What is the filter?

Answer 7

The vocal tract

Question 8

The source

Answer 8

The larynx has a set of cartilage which all do different things

Question 9

Phonation (production): vibration of the vocal folds

Answer 9

When we speak, we use our vocal cords inside the larynx
air expelled out of the lungs provides energy to the oscillators = the vocal cords
this cyclic opening/closing of the glottis generates a sound wave called the glottal wave

Question 10

How many times does the opening and closing of the glottis occur when we speak?

Answer 10

130 times for males

240 times for females

Question 11

What is the most common organ used in communication?

Answer 11

Larynx

Question 12

What are typical vocal sounds composed of?

Answer 12

Several sinusoidal waves which appear on spectrograms as evenly spaced, parallel, narrow, frequency componants

Question 13

What is the fundamental frequency?

Answer 13

The lowest of the parallel frequency components
The fundamental frequency determines the pitch
the variation of it with time determines the fundamental frequency contour

Question 14

What are harmonics?

Answer 14

Multiples of the fundamental frequency

Question 15

What is the pitch of a voice?

Answer 15

The perceived height of a voice

determined by the fundamental frequency

Question 16

What controls the vocal folds vibration rate?

Answer 16

The length, mass, tension and stiffness of the vocal folds affect the fundamental frequency: the longer and heavier the folds, the lower the pitch (I you want to speak low pitch, relax folds so mass is heavier, if you tense, speak with high)

Gender/age variation - children have shorter folds than women, than men

Question 17

Age and gender affects on fundamental frequency

Answer 17

strong sexual dimorphism: males have longer vocal folds
in pre puberty, there are no differences in vocal fold length and pitch, however, there is a dramatic enlargement of the larynx which occurs in males at puberty. Castrated males have female voices, females with testosterone develop males voice

Question 18

How much bigger is the male larynx?

Answer 18

40% bigger
pitch is 80% lower
male - 24mm
female - 17mm

Question 19

The filter

Answer 19

This is the vocal tract

Question 20

What happens to the larynx in the first few years?

Answer 20

It descends - newborns can suckle and breathe at the same time, but adults will choke if they do this

Question 21

What is the bad thing about having a descended larynx?

Answer 21

We could choke - evolutionary cost

Question 22

What cavity is created when the larynx descends?

Answer 22

The pharynx - a two tube vocal tract, with the tongue in the middle

Question 23

What are vocal tract resonances?

Answer 23

Formants (concentration of energy) - they shape the spectral structure of the speech signal, they are central to human speech as they provide the acoustic variation at the basis of vowels and consonants

Question 24

What do longer vocal tracts produce?

Answer 24

Lower formants

Question 25

Is the distribution of energy homogeneous?

Answer 25

Not across frequencies, some frequencies have more energy than others

Question 26

What do peaks and valleys represent?

Answer 26

The resonances that take place in the cavities of the vocal tract

Question 27

How does the vocal tract length affect voice gender in adults?

Answer 27

Males are 10% taller than females, the descent of the larynx results in a 1.2 sexual dimorphism in vocal tract length
the adult male vocal tract (16.5cm) is longer than the female vocal tract (14cm). as a consequence, formants are on average 20% lower in adult males than females

Question 28

How does the vocal tract length affect voice gender in kids?

Answer 28

In children, body size is identical and vocal apparatus is not sexually differentiated before puberty, however we can discriminate between girls and boys

Question 29

Why can we discriminate between girls and boys despite them having the same vocal tract length?

Answer 29

They mimic adults
boys round (constrict) their lips
girls pull their lips back and talk with a smile
children learn to achieve gender differences by imitating differences that exist between adults