Melissa Baese-Berk

Both environmental noise and talker-related variation (e.g., accented speech) can create adverse listening conditions for speech communication. Individuals recruit additional cognitive, linguistic, or perceptual resources when faced with such challenges, and they vary in their ability to understand degraded speech. However, it is unclear whether listeners employ the same additional resources when encountering different types of challenging listening conditions. In the present study, we compare individuals’ ability on a variety of skills —including vocabulary, selective attention, rhythm perception, and working memory—with transcription accuracy (i.e., intelligibility scores) of speech degraded by the addition of speech-shaped noise or multi-talker babble and/or talker variation (i.e., a non-native speaker). Initial analyses show that intelligibility scores across degradations of the same class (i.e., either environmental or talker-related) significantly correlate, but correlations of intelligibility scores across degradation classes are weaker. The relationship between intelligibility scores and cognitive-linguistic skills is similar, showing that while vocabulary and working memory correlate with multiple degradation types, rhythm perception only correlates with environmental degradations. Taken together, these results indicate that listeners may recruit different resources when faced with different classes of listening challenges.

Many theories predict the presence of interactive effects involving information represented by distinct cognitive processes in speech production. There is considerably less agreement regarding the precise cognitive mechanisms that underlie these interactive effects. For example, are they driven by purely production-internal mechanisms (e.g., Dell, 1986) or do they reflect the influence of perceptual monitoring mechanisms on production processes (e.g., Roelofs, 2004)? Acoustic analyses reveal the phonetic realisation of words is influenced by their word-specific properties – supporting the presence of interaction between lexical-level and phonetic information in speech production. A second experiment examines what mechanisms are responsible for this interactive effect. The results suggest the effect occurs on-line and is not purely driven by listener modelling. These findings are consistent with the presence of an interactive mechanism that is online and internal to the production system.