With abstracts and commentary by Dr. Anne Lawrence

1. Wolfe V, Ratusnik D, Smith F, Northrop G (1990) Intonation and Fundamental Frequency in Male-to-Female Transsexuals. J Speech Hearing Disord 55: 43-50.20 male-to-female transsexuals produced speech recordings for acoustic analysis and listener evaluation. Listeners identified 9 of the speakers as female, and 11 as male. The speakers identified as female had higher fundamental frequencies (F0) (average 172 Hz.; range 155-195 Hz.) than those identified as male (average 118 Hz.; range 97-145 Hz.). F0 was the the factor most highly correlated with a more feminine voice rating (r=.89).Speakers identified as female had less extensive downward intonations; a larger percentage of upward intonations; and a smaller percentage of level (unchanging) intonations These percentage differences were quite small, averaging less than 5% of all phonations. All of these items were much more weakly correlated with perceived femininity than was F0. Interestingly, speakers identified as female had a higher percentage of downward frequency shifts (defined as frequency changes between phonations), and fewer level (unchanging) shifts.

Another interesting finding was that the speaker with the voice considered most feminine actually had the lowest F0 (155 Hz.) of all the speakers rated female; her rating was possibly due to her very high percentage of upward intonation changes.

Take-home lessons

1. It appears that fundamental frequency (F0) is more important than intonation pattern as a cue to femininity in the voice. 155 Hz. seems to be an important threshold; speakers with F0s of 155 Hz. or higher were always rated as female, while those with F0s of 145 or below were never rated as female.

2. Once the F0 threshold has been crossed, a relatively small change in intonation pattern (with more intonation variability generally, and more upward intonations specifically) contributes substantially to perceived femininity in the voice.

3. Günzburger D (1995) Acoustic and Perceptual Implications of the Transsexual Voice. Arch Sexual Behav 24: 339-348.Six male-to-female transsexuals produced speech sample in their current, "female" speech mode, and in their former "male" mode. Listeners were able to distinguish and confirm the subjects' intended modes.Subjects speaking in their female mode displayed: higher fundamental frequencies (F0); greater pitch range; and decreased loudness. These findings are not surprising.

Interestingly, subjects speaking in female mode displayed significantly higher central values for the third formant frequency, F3. F3 is a harmonic of F0, and is associated with voice timbre, and with speaker sex identification -- females have higher average F3 values. F3 is dependent on airway resonance and size, with shorter vocal tracts producing higher F3 values. For this reason, and because speakers are not conscious of their formant frequencies, F3 is not usually considered to be subject to voluntary modification. The author speculates that some mechanisms by which the airway could be shortened might include: decreased lip rounding; retraction of the mouth corners (smiling); higher and more anterior tongue placement; and elevation of the larynx.

Take- home lesson

1. Experienced speakers can alter the timbre of their voice in a more feminine direction, possibly by using one or more of the technics listed above. This may not require formal speech therapy.Note: there are two earlier papers by Günzburger dealing with this same group of six transsexuals (although the one summarised above is the best):

2. An acoustic analysis and some perceptual data concerning voice change in male-female trans-sexuals (1993) Eur J Disord Commun 28: 13- 21.

3. Voice adaptation by transsexuals (1989) Clin Linguist Phonet 3: 163-172.
4. Spenser L. (1988) Speech Characteristics of Male-to-Female Transsexuals: A Perceptual and Acoustic Study. Folia Phoniat 40: 31- 42.8 male-to-female transsexuals, each using her "female" voice, produced speech recordings for acoustic analysis and listener evaluation. Paired recordings were obtained from age- and height-matched male and female controls. Listeners correctly identified the sex of all the controls; they identified 4 of the transsexual speakers as female, and 4 as male. The speakers identified as female all had average fundamental frequencies (F0) above 160 Hz. Those identified as male all had average fundamental frequencies (F0) of 160 Hz. or below. Pooling all subjects, transsexuals and controls, there was a high positive correlation (r=.93) between fundamental frequency and perceived "femaleness" of the voice.Not all female-rated transsexual speakers were considered to have "highly representative" female voices. From the limited data available, the author speculates that intonation pattern may be more important than formant frequency in determining to what extent a voice is considered "representatively female".

Take-home lesson

1. This is another report suggesting that some sort of important threshold for female voice identification occurs at approximately 160 Hz. (Wolfe et. al. found 155 Hz.).

2. Mount K, Salmon S (1988) Changing the Vocal Characteristics of a Postoperative Transsexual Patient: A Longitudinal Study. J Commun Disord 21: 229-238.A 63 y.o. male-to-female transsexual received speech therapy for 11 months. After four months, her fundamental frequency (F0) had risen from 110 Hz. to 205 Hz.; but she was still identified as male in telephone conversation. Additional therapy was aimed at raising airway resonance by encouraging elevation of the mandible and anterior tongue placement. Resonance, as measured by formant frequency F2, increased to female or near-female levels, resulting in the patient being consistently identified as female. Results were maintained five years post-treatment.

Take-home lesson

1. Some patients can learn to sound more feminine by increasing their airway resonance frequencies. This may require considerable time in therapy.

2. Coleman R (1983) Acoustic Correlates of Speaker Sex Identification: Implications for the Transsexual Voice. J Sex Res 19: 293- 295.The male vocal tract is about 2 cm. (not 20 cm.; that's a mis-print!) longer than the female vocal tract, resulting in lower vowel formant (resonance) frequencies in males. Formant frequencies provide cues to speaker sex identification in circumstances where the fundamental frequency (F0) is ambiguous.

Take home lesson

1. Relatively slight shortening of the male vocal tract (less than an inch) could effectively feminize its resonance characteristics. Smile; don't round your lips; and elevate your larynx!

2. Oates J, Dacakis G (1983) Speech Pathology Considerations in the Management of Transsexualism -- A Review. Br J Disord Commun 18: 139-151.The authors provide an introduction to transexualism for speech pathologists, including a concise review of the data concerning male/female speech differences. They include a valuable summary of differences in content, vocabulary, and style.

Take home lesson

1. This is a good article to give your speech therapist (as well as to read yourself). It emphasises that there is more to feminine speech than pitch, resonance, and intonation.

© 1998 Anne A. Lawrence, MD

Source http://www.mindspring.com/~alawrence/speechlit.html