ABSTRACT
This chapter concerns the acoustic description of vowels. In acoustic studies of vowel quality, primary importance is attached to the frequencies of the vowel formants during the steady state of the vowel. In natural speech, vowels are rarely pronounced in isolation. For linguistic phoneticians, the most striking characteristic of vowel formants is the remarkable correspondence between plots of the frequencies of the first and second formants and the traditional vowel quadrilateral. The spectral integration hypothesis has been of great interest to linguistic phoneticians. Firstly, it has interesting implications for vowel classification. Secondly, this type of integration, if it does occur, is likely to be specific to speech and must take place after general processing in the auditory periphery, which applies to all types of sound. Another type of vowel occupying the central area of the chart is the class of so-called central vowels, that is, vowels for which the tongue position is, in traditional terms, neither front nor back.
