It has been traditional in phonetic research to characterize
monophthongs using a set of static formant frequencies, i.e., formant
frequencies taken from a single time-point in the vowel or averaged over
the time-course of the vowel. However, over the last twenty years a
growing body of research has demonstrated that, at least for a number of
dialects of North American English, vowels which are traditionally
described as monophthongs often have substantial spectral change. Vowel
inherent spectral change has been observed in speakers' productions, and
has also been found to have a substantial effect on listeners'
perception. In terms of acoustics, the traditional categorical
distinction between monophthongs and diphthongs can be replaced by a
gradient description of dynamic spectral patterns. This book includes
chapters addressing various aspects of vowel inherent spectral change
(VISC), including theoretical and experimental studies of the
perceptually relevant aspects of VISC, the relationship between
articulation (vocal-tract trajectories) and VISC, historical changes
related VISC, cross-dialect, cross-language, and cross-age-group
comparisons of VISC, the effects of VISC on second-language speech
learning, and the use of VISC in forensic voice comparison.