Speech characteristics of monozygotic twins and a same-sex sibling: an acoustic case study of coarticulation patterns in read speech.

This case study reports on an acoustic investigation of the motor speech characteristics of a set of young adult male monozygotic (MZ) twins and compares them to those of an age- and sex-matched sibling who participated in the study 2 years later to match for demographic factors. Coarticulation patterns were investigated from read samples of consonant-vowel sequences in monosyllabic words containing a variety of consonants and vowels. This was done by examining F(2) vowel onsets and F(2) vowel targets, plotted as F(2) locus equations. Data were processed for between-sibling differences using a number of statistical tests. Results indicated that the MZ twins displayed F(2) parameters and coarticulation patterns which were more similar than those of their age- and sex-matched sibling. The results of this case study therefore suggest that acoustic phonetic parameters used to index coarticulation patterns have the potential to profile some of the similarities and differences in the speech characteristics of genetically related individuals.

Vocal characteristics in pre-adolescent and adolescent children: a longitudinal study.

A number of cross-sectional studies have been reported for the fundamental frequency and formant frequency data in the voices of a group of 20 pre-adolescent children aged between 6 and 10 years (Whiteside, S P, Hodgson, C. Acoustic characteristics in 6-10-year old children's voices: some preliminary findings, Log Phon Vocol 1999; 24: 6-13, Whiteside, SP, Hodgson, C. Some acoustic characteristics in the voices of 6-10-year-old children and adults: a comparative sex and developmental perspective, Log Phon Vocol 2000; 25: 122-132). About 15 of the children who participated in these earlier studies, participated in a follow-up study approximately 42 months later. Their speech data were recorded and analysed acoustically to investigate longitudinal patterns of development in their voices by examining data for fundamental frequency and the first three formant frequencies of a phrase final vowel. Data obtained from this follow-up study (Time 2) were compared with earlier corresponding data (Time 1). The findings of this study indicated that there was evidence for maturation in the voice parameters of all subjects between Time 1 and 2, with changes being observed for the majority of comparisons for parameters, across age and sex. In addition there was also evidence of individual differences in the maturational patterns which were observed. These individual differences highlight the degree of variation which occurs in the developmental changes of voice characteristics.

College-age males' ability to produce the acoustic properties of an aging voice: some suggestions for further exploration.

Manning, et al. recently reported on the ability of college-age males to imitate the voice of an aging male. This commentary briefly discusses how their data could be extended to support their published findings.

Sex-specific fundamental and formant frequency patterns in a cross-sectional study.

An extensive developmental acoustic study of the speech patterns of children and adults was reported by Lee and colleagues [Lee et al., J. Acoust. Soc. Am. 105, 1455-1468 (1999)]. This paper presents a reexamination of selected fundamental frequency and formant frequency data presented in their report for ten monophthongs by investigating sex-specific and developmental patterns using two different approaches. The first of these includes the investigation of age- and sex-specific formant frequency patterns in the monophthongs. The second, the investigation of fundamental frequency and formant frequency data using the critical band rate (bark) scale and a number of acoustic-phonetic dimensions of the monophthongs from an age- and sex-specific perspective. These acoustic-phonetic dimensions include: vowel spaces and distances from speaker centroids; frequency differences between the formant frequencies of males and females; vowel openness/closeness and frontness/backness; the degree of vocal effort; and formant frequency ranges. Both approaches reveal both age- and sex-specific development patterns which also appear to be dependent on whether vowels are peripheral or nonperipheral. The developmental emergence of these sex-specific differences are discussed with reference to anatomical, physiological, sociophonetic, and culturally determined factors. Some directions for further investigation into the age-linked sex differences in speech across the lifespan are also proposed.

Developmental trends in voice onset time: some evidence for sex differences.

This study reports on an investigation into the voice onset time (VOT) patterns of the plosives /p b t d/ in a group of 30 children aged 7 (n = 10), 9 (n = 10) and 11 (n = 10) years. Equal numbers of girls and boys participated in the study. Each child named a series of letter objects to elicit /p b t d/ in a syllable onset position with a fixed vowel context. VOT data were examined for age, sex and plosive differences with the following hypotheses: Firstly, that there would be sex differences in the VOT patterns of preadolescent children. Secondly, that the sex differences in VOT patterns would be linked to age and development, and that these would eventually become marked by the age of 11 years, by which time adult-like VOT values should have been achieved. Finally, that the extent of sex and age differences would be dependent upon the plosive being investigated. Results indicated patterns of decrease with age in the VOT values of /p b/ for the boys, with some evidence of increases in the VOT values of /t/ for the girls. In addition, 'voiced' and 'voiceless' cognates showed a more marked bimodal distribution in the girls' VOT patterns. This bimodal distribution was investigated by examining the degree of difference between the VOT values of voiced and voiceless cognate pairs /p b/ and /t d/, and examining the effects of age, sex and cognate pair. These results indicated that more marked sex differences in the 'voiced'/'voiceless' contrast emerged between the data of the 9- and 11-year-olds, a pattern, which was more marked for the alveolar plosives. These preliminary results confirmed all three hypotheses. The findings are presented and discussed both within a developmental and sociophonetic framework.

Comment on delayed left-ear accuracy in dichotic listening.

Moulden and Persinger recently reported on the emergence of left-ear accuracy during childhood and adolescence. This commentary briefly discusses their findings with reference to previous studies that have reported on dichotic listening paradigms and, in particular, those in which a left-ear focus was used as a behavioral probe sensitive to developmental sex differences.

Some acoustic characteristics in the voices of 6- to 10-year-old children and adults: a comparative sex and developmental perspective.

This study is a follow-up investigation of some of the acoustic characteristics reported for a group of twenty 6-, 8- and 10-year-old children's voices (Whiteside SP, Hodgson C. Log Phon Vocol 1999; 24: 6-13) and compares the data of these children with data from a group of nine adults. The acoustic characteristics for both the children and the adults were examined as a function of age and sex. Fundamental frequency (F0) and the standard deviation (SD) of F0 were investigated for the entire duration of a phrase-final vowel. In addition, the first three formant frequencies of the midpoints for the phrase-final vowel were also investigated, with reference to phonetic context. All acoustic parameters were investigated by examining the age, sex and context-determined differences. Results indicated significant age differences for all acoustic parameters investigated, which were characterized by a general decrease in the frequency values of parameters with increasing age. In addition, significant sex differences were found for all parameters, with the females generally having higher formant frequency values than their male peers across all ages. Significant phonetic context differences were only found for the second formant frequency, with formant values being highest for the context "jar" and lowest for the context "bar". No significant interactions were found for age-by-context, sex-by-context or age-by-sex-context comparisons. Relative formant frequency differences were also examined using Fant's Kn factor, by considering sex-, age- and context-linked patterns. The data also provided some evidence for parallel developmental patterns in the different phonetic contexts of a phrase-final vowel. Furthermore, the results showed that there was some evidence of all three types of the aforementioned patterns in addition to phonetic context-determined changes in K2 factor values. The results reported here, therefore, provide further evidence for age- and sex-linked differences in the patterns of development and maturation of the vocal apparatus.

Identification of twins from pure (single speaker) and hybrid (fused) syllables: an acoustic and perceptual case study.

This study describes a speaker-identification task carried out using two sets of single monosyllables and two sets of hybrid monosyllables prepared from monosyllabic words spoken by a set of monozygotic twins. The task was carried out by 6 listeners who were all very familiar with the twins and by the twins themselves. The identification scores for the pure syllables showed that both twins were identified with accuracy above chance; however, the percentage scores were less than perfect in both cases (71.4% and 72.9%). Analysis of the identification scores for the hybrid syllables showed that listeners had difficulty in attributing the hybrid syllables to a single twin. This was confirmed by the lack of significance in three binomial tests. The pure syllables were analysed acoustically to obtain a set of acoustic parameters for each twin. The results of the perceptual study are discussed with reference to the acoustic parameters. In addition, the implications of the study for issues in speaker identification are considered.

Some temporal characteristics of phrases produced by 6- to 10-yr.-old children.

20 children aged 6 (n = 6), 8 (n = 6), and 10 (n = 8) years, with equal numbers of boys and girls participated in a picture-naming task. Some temporal parameters of the speech data were examined. These included total phrase duration, duration of speaking time, and duration of pauses. Both age and sex differences were found. These results are presented and discussed briefly.

Note on voice and perturbation measures in simulated vocal emotions.

This brief study presents and discusses a set of acoustic correlates for a number of vocal emotions (neutral, cold anger, hot anger, happiness, sadness, interest, and elation) simulated by two actors. Five short all-voiced sentences were used in the simulations. The 70 sentences (2 actors x 5 sentences x 7 emotions) were digitised and a number of acoustic analyses were carried out, which included a number of voice and perturbation measures.

A comment on women's speech and its synthesis.

A brief update of sex differences in voice characteristics points to the style and linguistic convention in residual differences after processes of normalisation in phonetic studies and phonetic realizations in read speech as these affect speech synthesis.

Acoustic characteristics of vocal emotions simulated by actors.

This paper reports on a set of acoustic measures of vocal emotions simulated by a skilled actor and actress who read 12 short sentences. The emotions simulated were Neutral, Cold Anger, Hot Anger, Happiness, Sadness, Interest, and Elation. Acoustic measures were examined for digitised samples of the 168 sentences (2 speakers x 12 sentences x 7 emotions). These measures included the over-all mean energy, standard deviations of energy, mean fundamental frequency, mean values of the first six formant frequencies and their corresponding frequency bandwidths, mean durations of utterance, and mean articulation rate. Results displayed both similarities and differences in the acoustic measures of the two actors' simulations of the different emotions. These are presented and discussed.

Identification of a speaker's sex: a study of vowels.

An experiment was carried out to test whether three phonetically naive listeners were able to identify a speaker's sex from brief natural vowel segments. All speech segments presented to the listeners were extracted from sentences spoken by members of a group of three women and three men with a British General Northern accent. Analysis showed that listeners were able to identify the speaker's sex from the vowel segments with high accuracy (a mean score of 98.9%, p < .001). Acoustic analyses were subsequently carried out to quantify the acoustic and phonetic differences related to the sex of the speakers. Fundamental frequencies and format frequencies of the vowel stimuli were investigated. The men generally had lower values of both than the women.

Identification of a speaker's sex: a fricative study.

An experiment was carried out to test whether three phonetically naive listeners were able to identify the speaker's sex from brief (30 msec. to 100 msec.) voiceless fricative segments. All speech segments were extracted from sentences spoken by members of a group of 3 women and 3 men with a British General Northern accent. The consonant segments were significantly identified by the listeners with an accuracy of 64.4%. A sample of the fricative segments was chosen to investigate acoustic and phonetic differences related to a speaker's sex, using spectrographic analysis. Analysis showed that on the average the frication of the women's voiceless fricatives was significantly higher in frequency than that of the men.

Speakers' sex differences in voice onset time: a study of isolated word production.

This report presents a brief study into sex differences of speakers in the voice onset time of English plosives that are stressed in both word-initial and prevocalic positions. 36 isolated words were spoken by 5 men (age range 25 to 37 yr., M: 34.2 yr.) and 5 women speakers (age range 28 to 38 yr., M: 32.6 yr.) who were subjects. Analysis showed that the women speakers had on the average relative to the men, longer voice onset time values for voiceless plosives and shorter voice onset time values for the voiced plosives.

A reconceptualisation of apraxia of speech: a synthesis of evidence.

This paper presents a reconceptualisation of apraxia of speech (AOS) and reviews a range of acoustic and articulatory data which have been reported on apraxia of speech. Data from both domains, and previous theoretical debate are discussed as support for this cognitive-based reconceptualisation.

Speakers' sex differences in voice onset time: some preliminary findings.

This study presents a brief investigation into sex differences of speakers in the voice onset time of English plosives that are stressed in both word-initial and prevocalic position. 72 short phrases were presented to 5 men (range 25 to 37 years, mean age 34.2 yr.) and five women speakers (range 28 to 38 years, mean 32.6 yr.). Analysis showed that the women as speakers had on average, longer voice onset time values than their male peers.