Processing speech of varying intelligibility

In this talk we examine how variation in intelligibility impacts speech processing with insights from behavioral and neuroimaging studies. We discuss a set of experiments that explore the extent to which listener-oriented speaking style changes, sentence context, and visual information contribute to enhanced word recognition in challenging listening conditions. We further examine whether these same enhancements impact speech processing beyond word recognition, namely recognition memory for sentences. The results show that both signal-related and contextual enhancements lead to improved speech recognition in noise and, crucially, to a substantially better sentence recall. We then discuss studies examining neural mechanisms involved in processing speech of varying intelligibility using fMRI. Previous fMRI studies have examined speech intelligibility by using artificially degraded speech stimuli. Few studies have examined natural variation in intelligibility. Here we present neuroimaging data from two studies that examine natural variations in speech intelligibility (native vs. non-native speech; audio versus audiovisual speech). Overall, combined insights from behavioral and neuroimaging studies provide important additions to our understanding of how different sources of variability in the speech signal affect speech processing and memory representations.