Uncovering Tonal and Temporal Correlates of Phrasal Prominence in Medʉmba.

Characterizing prosodic prominence relations in African tone languages is notoriously difficult, as typical acoustic cues to prominence (changes in F0, increases in intensity, etc.) can be difficult to distinguish from those which mark tonal contrasts. The task of establishing prominence is further complicated by the fact that tone, an important cue to syllable prominence and prosodic boundaries cross-linguistically, plays many roles in African languages: tones often signal lexical contrasts, can themselves be morphemes, and can also interact in key ways with prosody. The present study builds on phonological generalizations about tonal patterns in Medʉmba, a Grassfields Bantu language, and uses the speech cycling paradigm to investigate relative timing of syllables varying in phrase-level prominence. Specifically, we investigate timing asymmetries between syllables hypothesized to occur at the edge of a phonological phrase, which carry a high phrase accent, and those in phrase-medial position, which do not. Results indicate significant differences in the temporal alignment of accented versus non-accented syllables, with accented syllables occurring significantly closer to positions established as prominence-attracting in previous speech cycling research. We show that these findings cannot be attributed to differences in tone alone. Findings demonstrate the importance of relative temporal alignment as a correlate of prosodic prominence. Findings also point to increased duration as a phonetic property which distinguishes between syllables bearing phrasal prominence from those which do not.

Temporal Coordination and Prosodic Structure in Autism Spectrum Disorder: Timing Across Speech and Non-speech Motor Domains.

Individuals with autism spectrum disorder (ASD) often exhibit disordered speech prosody, but sources of disordered prosody remain poorly understood. We explored patterns of temporal alignment and prosodic grouping in a speech-based metronome repetition task as well as manual coordination in a drum tapping task among Cantonese speakers with ASD and normal nonverbal IQ and matched controls. Results indicate similar group results for prosodic grouping patterns, but significant differences in relative timing and longer syllable durations at phrase ends for the ASD group. Variability on the speech task was significantly correlated with variability on the drumming task, consistent with the view that impairment in both speech and non-speech motor domains can be linked with deficits in temporal processing.

An Acoustic Characterization of Prosodic Differences in Autism Spectrum Disorder and First-Degree Relatives.

This study examined prosody through characterization of acoustic properties of the speech of individuals with ASD and their parents, during narration. A subset of utterances were low-pass filtered and rated for differences in intonation, speech rate, and rhythm. Listener ratings were minimally related to acoustic measures, underscoring the complexity of atypical prosody in ASD. Acoustic analyses revealed greater utterance-final fundamental frequency excursion size and slower speech rate in the ASD group. Slower speech rate was also evident in the ASD parent group, particularly parents with the broad autism phenotype. Overlapping prosodic differences in ASD and ASD Parent groups suggest that prosodic differences may constitute an important phenotype contributing to ASD features and index genetic liability to ASD among first-degree relatives.

Internal and contextual cues to tone perception in Medʉmba.

This study presents results of an identification experiment with speakers of Medʉmba, a Grassfields Bantu language, aimed at evaluating the relative effects of f0 and duration in cuing tonal contrasts, as well as the role of lexical vs non-speech pitch contexts in biasing tone perception. Results show that duration is a cue for tone perception, with the influence of duration strongest where target f0 values were lower. Lexical tone perception is also sensitive to the identity of a preceding lexical tone, but not to the presence of a preceding non-speech pure tone.