Commentary on ‘Reading waveforms’

Abstract

The previous issue of the Journal contained a discussion by Peter Ladefoged about interpreting the information in a speech waveform (JIPA, 21, 32–34), noting that examination of waveforms displays is becoming commonplace with the easy availability of personal computer tools for digitizing and editing. As Ladefoged noted:“Several aspects of sounds are clearly distinguishable from the waveforms of a phrase. Stop closures are very evident, as are differences between voiced sounds which have repetitive waveforms and voiceless sounds which do not. Differences in amplitude can be used to distinguish high frequency, high intensity sibilants from lower intensity non-sibilant fricatives; and nasals and laterals usually have smaller amplitudes than the louder adjacent vowels. An expanded view of the waveform allows us to see intervals between peaks in the damped wave of a voiced sound, and thus to calculate the frequency of the first formant. Nasals can often be distinguished from vowels in these expanded waveforms, not only by their smaller amplitudes but also by the less clear formant structure.”