Vowels and speech production: gender differences

Presentation from Lina Hecker

Speaker CharacteristicsVenice International UniversityProf. Dr. Jonathan Harrington

17. October 2007

Introduction:• there have been some analyses of female speech in

the past→ focal point has been the male voice• female voice has a higher frequency range • men are more studied and they are regarded as the

standard to which everything else is compared• in this lecture you can hear some differences in the

speech of females and males based on adults• focus on dynamic articulatory and acoustic

consequences of differences in male and female vocal tract dimensions

• and the relationship between formant change and tongue movement

1. What are the dynamic articulatory and acoustic consequences of differences in male and female vocal tract dimensions?

(Simpson 2001)

• Simply illustrated in Goldstein (1980) using the mid-sagittal vocal tract dimensions

• models vocal tract growth from infant to adult and its acoustic products

• Goldstein draws together available anatomical dimension data from a number of qualitative and quantitative different sources

Conclusion of Figure 1:

• In the figure female stricture sizes are calculated as 80% of the male values.

• It shows superimposed tongue positions for female (solid) and male (dashed) [i] and [a].

• The distance from male [a] to [i] is ~11% greater than the analogous female distance.

• If you assume the same nominal articulatory speed and neglect inertia and acceleration, then the male V–V movement will also take 11% longer.

2. The relationship between the size of oral structures and its implications for

articulatory displacement and articulatory velocity.(Kuehn & Moll 1976)

• They showed that the subjects with larger oral structures, had larger articulatory displacement and employed greater articulatory velocity to traverse larger articulatory spaces.→ focused on the general consequences of differences in oral structure size → did not discuss the more wide-ranging implications of their findings for gender specific consequences in articulatory behavior and its acoustic products

Explanation of Figure 2:• In the next figure you can see a hypothetical

male and female F1 paths for open–close vowel movement, assuming the same nominal tongue body movement speed of 200mm/s.

→ the male acoustic trajectory lasts longer than the female one

→ the linear acoustic rate of change of F1 for females is ~35% greater than the male value.

==> female tongue covers a shorter distance to achieve analogous targets, and corresponds to a greater acoustic distance.

Conclusion of Figure 2:• males and females aim for analogous phonetic vowel

targets in CVC sequences • if they move their articulators at the same speed, and

if they are operating within the same durational framework → females reach their target earlier

• female degree of openness is greater than the male one

• females exhibit less undershoot than males → undershoot increases from close to open vowel

categories==> despite dimensional differences, targets are

attained at approximately the same time with a difference in articulatory speed

3. The Relationship between formant change and tongue movement

main articulatory-acoustic patterns found in diphthongs (Simpson 2001)

• average male and female pellet and formant tracks are similar in form

• female speakers cover a greater acoustic space both in linear (Hz) and nonlinear (Bark) terms

• The articulatory distance covered by the two posterior lingual pellets during the vocalic stretch is greater for male speakers

• the dorso-tectal stricture size defined by the two posterior lingual pellets is smaller for female speakers throughout the vocalic stretch

• mean pellet speeds are greater for male than female speakers

3.1. Data: UW-XRMBDB (Westbury, 1994) • data set for examining gender-specific differences

in the relationship between articulation and its acoustic products

• contains acoustic and articulatory records from 26 female and 22 male speakers (age 18-37), speaking Upper Midwest dialect of Am. English

• linguistic (e.g. reading text) and non-linguistic (e.g. swallowing) tasks

• articulatory data consists of 8 gold pellets

• 4 lingual pellets are placed along the midline of the tongue

3.2. Methoduse stretches of utterance to investigate the dynamic relationship between acoustic and articulatory activity which fulfill 3 criteria

1. large amounts of articulatory and acoustic movement;

2. continuous voicing throughout the stretch to facilitate reliable automatic formant tracking;

3. repetition by the same speaker of the same expression containing a suitable stretch.

“The coat has a blend of both light and dark fibers.”

‘‘They all know what I said’’

A: Formant analysis

• analysis of the vocalic stretch of “they all” made with the ESPS program formant

• nominal default value of F1 was increased by 10% to 550Hz for female speakers

• analysis times were extended by 25ms beyond the segment start and end times

• formant tracks of the 239 tokens were visually checked for tracking errors

• each set of formant tracks was resampled to provide 11 temporally equidistant formant records

• 11 points provide a good definition of formant movement throughout the vocalic stretch

B: Pellet position

• pellet position of the UW-XRMBDB are stated in a coordinate system

• The normalization method redefines the position of the pellets on the tongue surface, with respect to their distance from the tip of the upper incisors.

• normalization allows to compare values from speakers with different palate outline lengths

• raw pellet positions were averaged separately for males and females

• male and female average palate outlines were created using individual palate outlines, resampled at 0,5mm intervals

3.3. Results

3.3.1. Duration:• a one-tailed t-test for the V-V stretches shows that

the mean female duration is greater than the male one

→ no significant difference was found between the male and female durations of the utterances

• in other studies there were also found longer female durations for diphthongs (Simpson 2001) and monophthongs (Hillenbrand, Getty, Clark & Wheeler 1995)

3.3.2. Formant tracks• at the 11 equidistant measurement points means

and standard deviations of F1-F3 were calculated for males (right) and females (left) tokens. (next fig)

• formant values for the V-V stretch for “they all” can only cautiously compared with the results found in the literature

1. speakers in the UW-XRMBDB speak an Upper Midwest American English

2. vowels are from the initial part of the utterance,

particularly “they” being utterance-initial, unstressed and preceding a stressed back open vowel → expect a more centralized vowel than you would find in isolation or utterance finally

• In the next figure you can see a graphical comparison of the mean male and female formant tracks, converted to the Bark scale.

• In linear (Hz) terms, female acoustic excursion within the vocalic stretch is greater for both F1 and F2

• In non-linear (Bark) terms, situation is different. The mean tracks for F2 and F3 run parallel with little change and a distance between them throughout the vocalic stretch.

• difference in mean F1 is 0,74 Bark at the beginning and is 1,58 Bark (more than twice) by the end of the stretch

→ suggesting a closer male vowel or a more open female quality

→ more open the vowel quality, the larger the difference becomes between female and male F1

Explanation of figure 5:• during vocalic stretch tongue body makes a small

upward moving before moving backwards and downwards

• F1 is determined by the apico-dental stricture of “they” over the initial part of the stretch (t1-t4)

• at the final part of the stretch (t5-t11) the tongue body is lowered, resulting in an increase in the size of the dorso-palatal stricture defined by T2–T4

• F2 rises (t2-t4) to reach a plateau at (t3-t4) for the closing phase of the diphthong

• F2 falls continuously as dorso-palatal stricture size increases and the tongue moves back

• rise in F3 can be related to the lowering and backing of the tongue body causing pharyngeal narrowing

3.3.3. Pellet position and speeds• Fig. 6 shows the pellet position of the 4 lingual pellets

• T1-T4 at each of the 11 measurement points for female and male speakers

• transformed and normalized values are shown in (a)

• in (b) raw values are plotted together with average palate outlines and pharynx line segments can be seen

• arrows indicate the direction of movement over time

• (b) shows the mean size, shape and location of the male and female pellet trajectories

• in the transformed data (a), the palate has been ‘flattened’

→ must be interpreted more carefully

Explanation of Figure 6:• both transformed and raw data bring out the larger

male dorso-palatal strictures defined by T3 and T4

• laminal and apical strictures are not different for males and females

• transformed data encode the distance between the palate and the pellets

• higher location of the female trajectories shows the different stricture size (T3-T4)

• T-test proves that for females the palate-pellet distance for T3-T4 is smaller

• average lengths of the pellet trajectories during the vocalic stretch are shorter for females

• posterior male lingual pellets T3-T4 travel a greater distance than the female pellets and they stay in contrast to the smaller acoustic space traversed by the male speakers

• these gender differences stand in contrast to findings in (Hashi et al. 1998) where no gender influence on isolated vowel tokens was found

• male dorsum travels a greater distance in a shorter time period (see 1.Duration) than the female one because the mean speed of the male posterior pellets (T3-T4) is higher

Explanation of Figure 7:• the next figure summarizes the average pellet speeds

at each of the 11 measurement points

• for the anterior pellets T1-T2 the male and female speed is not significantly different over the whole vocalic stretch

• for T3-T4 the initial and final portions are similar as well

• whereas the mean speeds of T3-T4 are at the highest point you can see significantly higher male speeds

→ compensation by both males and females is necessary to achieve the same targets, despite differences in articulatory space

Conclusion of Figure 7:• gender-specific stricture differences are restricted to

posterior region of the oral cavity

→ degree of male palatal doming is higher and creates a greater articulatory space to cross

• there are nonuniform differences in the relation of oral to pharyngeal cavity length and nonuniform differences in palate shape

→ this has nonuniform dynamic consequences for tongue movement

4. Discussion• for the same V-V sequences male and female tongue

movements and their acoustic and perceptual products are similar in shape and structure

• difference between male and female F1 increased acoustically with the degree of vowel openness

• male speakers had a shorter stretch duration

→ the speed of tongue dorsum displacement was higher

• size of male and female articulatory spaces is different and stands in an inverse relationship to the size of their acoustic products

• for the V-V sequences male and female pellet tracks have a similar form and differ only in size and position

• male and female speakers a operating with similar speeds of tongue movements

• assume that the slower (female) articulatory movements require more time and faster (male) ones less

• larger vowel space for women

→ women speak more clearly and articulate more because it is the prestige form for female

• women produce longer vowels than men

• possibly speakers adopt different articulatory strategies to arrive at tokens of the same phonological categories

→ many of the hypothetical consequences are speculation

→ no proof whether 2 speakers aim for similar targets when they produce tokens of the same phonological categories in a language

→ no classification that tokens of the same phonological categories are equivalent in articulatory, acoustic and perceptual terms

• several experiments draw conclusions based on a few informants

→ tendencies might be individual rather than gender based

• many reasons for difference between male and female speech

→ women tend to have a greater variation in their speech

→ female speech has been seen more difficult to analyse

5. References

• Simpson, A. P. (2002). Gender-specific articulatory-acoustic relations in vowel sequences. Journal of Phonetics, 30(3):417-435.

• Simpson, A. P. (2001). Dynamic consequences of differences in male and female vocal tract dimensions. Journal of the Acoustical Society of America, 109(5):2153-2164.

• Samuelsson, Y. (2006) Gender effects on phonetic variation and speaking styles: A literature study. GSLT Speech Technology Term Paper, autumn 2006.

• Goldstein, U. (1980) An articulatory model for the vocal tracts of growing children. Ph. D. Thesis, MA: M.I.T.

• Hashi, M., Westbury, J. R. & Honda, K. (1998) Vowel posture normalization, Journal of the Acoustical Society of America, 104, 2426–2437.

• Johnson, K., Ladefoged, P. & Lindau, M. (1993) Individual differences in vowel production, Journal of the Acoustical Society of America, 94, 701–714.

• Kuehn, D. P. & Moll, K. L. (1976) A cineradiographic study of VC and CV articulatory velocities, Journal of Phonetics, 4, 303–320.

Thank you for listening!