Individual variation in the frication of voiceless plosives in Australian English: a study of twins’ speech.

This study is an acoustic–phonetic examination of variation in Australian English consonant production. Group and individual patterns in the rates of frication of the voiceless plosives /p t k/ in Australian English are investigated. Previous studies on voiceless plosive production in Australian English have focused primarily on /t/, and these analyses have largely been auditory in nature. Further, whereas previous studies have focused on describing sociophonetic variation within Australian English, this study investigates speaker-specific variation. An analysis of twin speech, produced by young adult male speakers from Melbourne, is presented. The speakers are three identical twin pairs and one non-identical twin pair. The reason for studying twins, and identical twins in particular, is to explore the degree of phonetic difference between pairs of individuals who, theoretically, are as anatomically similar as possible and whose educational levels and home lives have been relatively the same. The speakers were recorded separately, engaging in spontaneous conversation with the first author in two sessions each. All /p t k/ tokens were categorized as fricated or closed using acoustic waveforms and wideband spectrograms. While /t/ was rarely fricated by any speaker, /p/ and /k/ exhibited a wide range of variation in the proportions of tokens fricated, both between speakers, and within twin pairs. Further, each individual's proportions of /p/ and /k/ tokens fricated were relatively consistent across the two recording sessions. Implications of these findings for descriptions of Australian English and theories of speaker characteristics are discussed.