Speech Science Forum - Omnia Ibrahim (Saarland University)

Abstract:

Speakers tend to speak clearly in noisy environments, while they tend to reserve effort in predictable contexts. It is unclear how these two communicative demands are met.  In this talk, I will present 2 studies investigating the acoustic realizations of syllables in predictable vs. unpredictable contexts across different background noise levels.

Study 1 focuses on the acoustic adjustments made by German native speakers (n=38) when producing 60 CV syllables in two predictability contexts under three noise conditions. We analysed various acoustic measures such as duration, intensity (average and range), F0, and vowel formants. The presence of noise yielded significantly longer duration, higher average intensity, larger intensity range and higher F0. Noise levels affected intensity (average and range) and F0. Low predictability syllables exhibited longer duration and larger intensity range. However, no interaction was found between noise and predictability. This suggests that noise-related modifications might be independent from predictability-related changes, with implications for including channel-based and message-based formulations in speech production.

Study 2 explores the impact of syllable-based predictability on the durational cues of the phonological stop voicing contrast in German, specifically voice onset time (VOT), closure duration (CD), and voicing during closure (VDC). Cross-linguistic evidence suggests that syllables in predictable contexts have shorter duration compared to unpredictable contexts. However, the uniformity of the predictability effect on phonetic cues within a segment remains unclear. Our results showed an interaction effect of predictability and the voicing status of the target consonants on VOT, but a uniform effect on closure duration and VDC. This interaction effect on a primary cue like VOT indicates a selective effect of predictability on VOT, but not on CD or VDC. This suggests that the effect of predictability is sensitive to the phonological relevance of a language-specific phonetic cue.