Acoustic characteristics of central vowels in American English.

Surprisingly little is known of the acoustic characteristics of the central vowels caret (//) and (/ə/), even though they occur frequently in English and contribute significantly to its rhythmic characteristics [Umeda, J. Acoust. Soc. Am. 58, 434–445 (1975)] Moreover, analyzes of schwa in Dutch [van Bergem, Speech Comm. 16, 329–358 (1995)] show that its acoustic characteristics are surprisingly variable and very much affected by surrounding context. This paper reports temporal and spectral measurements of the vowels // and /ə/ produced by 10 speakers (5 male and 5 female) from central Wisconsin. These vowels were produced in real words in a variety of phonetic environments in both a reading task (three different rates of speech) and in spontaneous speech. Descriptive analyzes will be presented as well as discriminant function analysis in which the acoustic measures are used to classify the two vowels. The effects of speech rate and speech material on the two vowels will also be examined.