The influence of social characteristics on speech perception.

Recent research has uncovered an intriguing relationship between vowel perception and social characteristics, so that the gender of a speaker appears to influence vowel perception (Johnson, Strand, and D'Imperio 1999). This thesis helps to shed light on the extent to which social characteristics inferred from a voice or a face can influence vowel perception. Due to a chain shift in New Zealand English, speakers of different ages produce different variants of the vowels in the words head and had. This thesis examines speech perception within the context of the chain shift in progress by analysing results from a series of perception experiments which were implemented using resynthesised vowel continua. In Experiment 2, the apparent age of each resynthesised voice was manipulated with the help of photographs in order to investigate whether the perceived age of a speaker can affect speech perception. The results provide evidence that people perceive vowel boundaries in different places, and that this difference can be predicted to some degree by the social characteristics of the perceivers. Additionally, the results suggest that social characteristics inferred from both a voice and a photograph can influence perception, as participants appear to have perceived the vowels differently depending on the perceived age and social class of the stimuli. These findings pose a problem for many current models of speech perception which fail to straight-forwardly account for variation in speech perception, let alone how this variation may be related to the social characteristics of the perceived social characteristics of the speaker. Taken together, the results support an ~xemplar-based model of speech perception as well as uncover some challenges for the application and predictions of current exemplar-based models