Formant Frequencies, Vowels and Diphthongs

Question 1

What is the role of the source filter theory?

Answer 1

Within the 2 stage process of the source filter theory, formant frequency and vowels relate to the 2nd stage (the filtering of the sound source)

Question 2

What is the function of the supralaryngeal filter?

Answer 2

The supra-laryngeal filter forms the differences between vowel sounds, also known as the vowel quality. They are independent of the activity of the larynx. Throughout speech production, the supralaryngeal filter is continually changing as speech production is a dynamic process.

Question 3

What are formant frequencies?

Answer 3

They are determined by the length and shape of the vocal tract which acts as an acoustic filter. The supralaryngeal vocal tract supralaryngeal vocal tract suppresses the transfer of sound energy at certain frequencies whilst letting maximum energy through at other frequencies. The frequencies at which local energy peaks are allowed to pass through the supra-laryngeal tract are formant frequencies.

Question 4

What are the Acoustics of vowels? (First Formant)

Answer 4

The first formant frequency represents vowel height.

High vowels= e.g /i/ and /u/ which have a relatively low f1 whilst low vowels e.g /a/ and /ae/ have a relatively high f1. The frequency of the first formant varies inversely with tongue height.

EXAMPLES
/i/ = the lowest (237 hz)
/ae/ = highest (654 hz)

• Same for fronted and backed vowels (e.g /u/ and /i/)= comparable of F1

Question 5

What are the acoustics of vowels? (Second Formant)

Answer 5

Measured by the distance between the first and second formant.

Frequency of F2 varies with the posterior-anterior dimension of vowel articulation e.g front vowels /i/ and /ae/ have a high frequncy F2 whilst the back vowels /u/ and /a/ share a low F2.

EXAMPLES

• [u] = F2-F1 = 867 hz
• [i] = F2-F1= 2000 hz

Question 6

What are the acoustics of vowels? (Third Formant)

Answer 6

Doesn’t change much e.g only provides info about rhoticity.

Rounding vowels= frequency of all formants are lowered by rounding. Lip rounding effects the length of the vocal tract (which causes formants to assume lower frequencies)

Neural vowels such as /3/ is open and behaves like a standing resonator (in british english , however in american english /3/ is rhotacised. In british english /3/ even distribution of formant frequencies

EXAMPLES:

back vowels use the most lip rounding, [a] [or] [o] and [u] (least to most rounded)

Question 7

How does Formant bandwidth differ in Vowels and Formants?

Answer 7

It increases with formant number e.g F1 = smallest bandwidth. However in general this has little effect on vowels

Nasal vowels have a greater bandwidth, but regular vowels have unusually narrow bandwidth.

Question 8

What is the Amplitude characteristic in vowels?

Answer 8

vowels have a relatively open vocal tract and so a high amplitude

Question 9

How are the acoustic characteristics of diphthongs similar to that of vowels?

Answer 9

Similar to vowels as produced with an open vocal tract, and well defined formant structure (they also serve as the nucleus of the syllable)

Question 10

How do vowel and diphthongs differ?

Answer 10

They cannot be defined by a single vocal tract shape or a single formant pattern.

produced by changing the articulator shape (hence the formant pattern) slowely during the stages of sound production

Question 11

What are some Anatomical differences affecting Formant frequency?

Answer 11

• Men have lower formant frequency on average (because they have bigger and longer supra-laryngeal vocal tracts)
• Lower formant frequencies contribute to the perception of lower pitched voices.

Question 12

What are the sex differences affecting Formant frequencies ?

Answer 12

There is still evidence for sex differences prior to the significant changes in adolescence

• There is also evidence that vowel spaces are far larger for women (in all languages)

Question 13

What are some other individual differences which effect the formants?

Answer 13

Accent, generation, age, SES and social group

Question 14

How does Deterding (1997) English study compare to Whiteside and Rixon’s Irish study (2003) and Peterson and Barney (1952) American study?

Answer 14

They all show different third formants in the vowel [er].

English= 2488 hz
American = 1690 hz
Irish= 1756 hz

Question 15

What did Kuhl (1997) find regarding cross language analysis in infant speech compared to adult speech?

Answer 15

When vowel formant frequencies (/i/ /a/ and /u/ ) were examined.

For all 30 mothers vowel triangles were significantly larger for IDS samples.

Expansion of the vowel spaces = large (92% overall across the languages)

IDS = example of hyper articulation which provides good vowel exemplars.

Question 16

What did Whiteside 2001 find ?

Answer 16

For both males and females there is a decrease in the K-age values for all 3 formant frequencies. younger females have higher F1 values compared to the women speakers.

Whilst a substantial degree of sex differences emerge after puberty for some vowels (ae, ao, iy, uw), others show a lower proportional increase after puberty (aa,ah,er,uh)

decreases in F1 for the adult women shown- may suggest age specific changes occuring in the vocal tracts of older females.

Question 17

What did Whiteside and Rixon (2003) find?

Answer 17

all 3 (twins and age/sex matched sibling) appear to have similar Formant frequency patterns, assuming they have similar vocal tract lengths.

The twins displayed higher F2 onset and F2 target values compared to their sibling, suggesting the twins many have greater physical similarities in their vocal tracts.

• F2 vowel onset similarities great in the twins, twins may have used similar articulatory dynamics at the onset of vowels in the CV sequence.

Question 18

What did Lee et al 1999?

Answer 18

at 11 years differentation of F2 and F3 patterns begin, and become fully distinguishable at around 15

• Between 10-15 formant frequencies decrease faster in males, reach lower levels than the females. Adult levels reached 15 for males, 14 for females.

Question 19

What did Whiteside (2001) find?

Answer 19

Younger females have a higher F1 than older Females. Both males and females , generally have all 3 lower formant frequencies as they increase with age.