Dialectal and generational variations in vowels in spontaneous speech

The pronunciation patterns across dialect regions in the United States are changing. This paper examines acoustic differences between the vowels of old and middle-aged adults produced in spontaneous speech. The new developments in regional vow-els systems found recently in citation-form vowels and in read speech were confirmed in the present analysis. While provid-ing additional evidence for the existence of sound change on the basis of spontaneous speech data, this work exemplifies the important challenges facing researchers using spontaneous speech in laboratory analyses such as the loss of fine experi-mental control or the usefulness of statistical assessment. Index Terms: dialect variation, sound change, spontaneous speech, vowel acoustics, spectral dynamics