Factors influencing speech perception in the context of a merger-in-progress

In New Zealand English there is a merger-in-progress of the NEAR and SQUARE diphthongs. This paper investigates the consequences of this merger for speech perception. We report on an experiment involving the speech of four New Zealanders-two male, and two female. All four speakers make a distinction between NEAR and SQUARE. Participants took part in a binary forced-choice identification task which included 20 NEAR/SQUARE items produced by each of the four speakers. All participants were presented with identical auditory stimuli. However the visual presentation differed. Across four conditions, we paired each voice with a series of photos-an "older" looking photo, a "younger" looking photo, a "middle class" photo and a "working class" photo. The middle and working class photos were, in fact, photos of the same people, in different attire. In a fifth condition, participants completed the task with no associated photos. At the end of the identification task, each participant was recorded reading a NEAR/SQUARE wordlist, containing the same items as appeared in the perception task. The results show that a wide range of factors influence accuracy in the perception task. These include participant-specific characteristics, word-specific characteristics, context-specific characteristics, and perceived speaker characteristics. We argue that, taken together, the results provide strong support fox exemplar-based models of speech perception, in which exemplars are socially indexed. (c) 2005 Elsevier Ltd. All rights reserved.