Michèle Pettinato

Developmental and gender-related trends of intra-talker variability in consonant production

This study investigates the effect of age and gender on the internal structure, cross-category distance, and discriminability of phonemic categories for two contrasts varying in fricative place of articulation (/s/-/∫/) and stop voicing (/b/-/p/) in word-initial tokens spoken by adults and normally developing children aged 9-14 yr. Vast between- and within-talker variability was observed with 16% of speakers exhibiting some degree of overlap between phonemic categories-a possible contribution to the range of talker intelligibility found in the literature. Females of all ages produced farther and thus more discriminable categories than males, although gender-marking for fricative between-category distance did not emerge until approximately 11 yr of age. Children produced farther yet also much more dispersed categories than adults with increasing discriminability with age, such that by age 13, childrens categories were no less discriminable than those of adults. However, childrens ages did not predict category distance or dispersion, indicating that convergence on adult-like category structure must occur later in adolescence.

Cross-accent intelligibility of speech in noise: Long-term familiarity and short-term familiarization

Listeners must cope with a great deal of variability in the speech signal, and thus theories of speech perception must also account for variability, which comes from a number of sources, including variation between accents. It is well known that there is a processing cost when listening to speech in an accent other than ones own, but recent work has suggested that this cost is reduced when listening to a familiar accent widely represented in the media, and/or when short amounts of exposure to an accent are provided. Little is known, however, about how these factors (long-term familiarity and short-term familiarization with an accent) interact. The current study tested this interaction by playing listeners difficult-to-segment sentences in noise, before and after a familiarization period where the same sentences were heard in the clear, allowing us to manipulate short-term familiarization. Listeners were speakers of either Glasgow English or Standard Southern British English, and they listened to speech in either their own or the other accent, thereby allowing us to manipulate long-term familiarity. Results suggest that both long-term familiarity and short-term familiarization mitigate the perceptual processing costs of listening to an accent that is not ones own, but seem not to compensate for them entirely, even when the accent is widely heard in the media.

The impact of variation in phoneme category structure on consonant intelligibility

Newman et al. [J. Acoustic. Soc. Am, 109, 1181-1196 (2001)] suggested that phoneme identification accuracy and speed for a given talker was affected by the degree of variability in their production of phoneme categories. This study investigates how intra-talker variability in the production of two phoneme contrasts varies with age and gender, and how this variability affects perception. Multiple iterations of tokens differing in initial consonants (/s/-/∫/, /p/-/b/) were collected via picture elicitation from 40 adults and 31 children aged 11 to 14; measures of within-category dispersion, between-category distance, overlap and discriminability were obtained. While females produced more discriminable categories than males, children produced farther yet more dispersed - and thus similarly discriminable - categories than adults. Variability was contrast-specific rather than a general talker characteristic. Tokens with initial /s/-/∫/ from pairs of adult and child talkers varying in between-category distance ...

Suprasegmental Characteristics of Spontaneous Speech Produced in Good and Challenging Communicative Conditions by Talkers Aged 9-14 Years.

Purpose This study investigated the acoustic characteristics of spontaneous speech by talkers aged 9-14 years and their ability to adapt these characteristics to maintain effective communication when intelligibility was artificially degraded for their interlocutor. Method Recordings were made for 96 children (50 female participants, 46 male participants) engaged in a problem-solving task with a same-sex friend; recordings for 20 adults were used as reference. The task was carried out in good listening conditions (normal transmission) and in degraded transmission conditions. Articulation rate, median fundamental frequency (f0), f0 range, and relative energy in the 1- to 3-kHz range were analyzed. Results With increasing age, children significantly reduced their median f0 and f0 range, became faster talkers, and reduced their mid-frequency energy in spontaneous speech. Children produced similar clear speech adaptations (in degraded transmission conditions) as adults, but only children aged 11-14 years increased their f0 range, an unhelpful strategy not transmitted via the vocoder. Changes made by children were consistent with a general increase in vocal effort. Conclusion Further developments in speech production take place during later childhood. Children use clear speech strategies to benefit an interlocutor facing intelligibility problems but may not be able to attune these strategies to the same degree as adults.

Is prosodic production driven by lexical development? Longitudinal evidence from babble and words.

This study investigated the relation between lexical development and the production of prosodic prominence in disyllabic babble and words. Monthly recordings from nine typically developing Belgian-Dutch-speaking infants were analyzed from the onset of babbling until a cumulative vocabulary of 200 words was reached. The differentiation between the two syllables of isolated disyllabic utterances was computed for f0, intensity, and duration measurements. Results showed that the ambient trochaic pattern emerged in babble, but became enhanced in words. Words showed more prosodic differentiation in terms of f0 and intensity and a more even duration ratio. Age or vocabulary size did not predict the expansion of f0 or intensity in words, whereas vocabulary size was related to the production of more even-timed syllables. The findings are discussed in terms of lexicalist accounts of phonetic development and a potential phonetic highlighting function of first words.

Expansion of Prosodic Abilities at the Transition From Babble to Words: A Comparison Between Children With Cochlear Implants and Normally Hearing Children

Objectives: This longitudinal study examined the effect of emerging vocabulary production on the ability to produce the phonetic cues to prosodic prominence in babbled and lexical disyllables of infants with cochlear implants (CI) and normally hearing (NH) infants. Current research on typical language acquisition emphasizes the importance of vocabulary development for phonological and phonetic acquisition. Children with CI experience significant difficulties with the perception and production of prosody, and the role of possible top-down effects is, therefore, particularly relevant for this population. Design: Isolated disyllabic babble and first words were identified and segmented in longitudinal audio–video recordings and transcriptions for nine NH infants and nine infants with CI interacting with their parents. Monthly recordings were included from the onset of babbling until children had reached a cumulative vocabulary of 200 words. Three cues to prosodic prominence, fundamental frequency (f0), intensity, and duration, were measured in the vocalic portions of stand-alone disyllables. To represent the degree of prosodic differentiation between two syllables in an utterance, the raw values for intensity and duration were transformed to ratios, and for f0, a measure of the perceptual distance in semitones was derived. The degree of prosodic differentiation for disyllabic babble and words for each cue was compared between groups. In addition, group and individual tendencies on the types of stress patterns for babble and words were also examined. Results: The CI group had overall smaller pitch and intensity distances than the NH group. For the NH group, words had greater pitch and intensity distances than babbled disyllables. Especially for pitch distance, this was accompanied by a shift toward a more clearly expressed stress pattern that reflected the influence of the ambient language. For the CI group, the same expansion in words did not take place for pitch. For intensity, the CI group gave evidence of some increase of prosodic differentiation. The results for the duration measure showed evidence of utterance final lengthening in both groups. In words, the CI group significantly reduced durational differences between syllables so that a more even-timed, less differentiated pattern emerged. Conclusions: The onset of vocabulary production did not have the same facilitatory effect for the CI infants on the production of phonetic cues for prosody, especially for pitch. It was argued that the results for duration may reflect greater articulatory difficulties in words for the CI group than the NH group. It was suggested that the lack of clear top-down effects of the vocabulary in the CI group may be because of a lag in development caused by an initial lack of auditory stimulation, possibly compounded by the absence of auditory feedback during the babble phase.