The Perception of Vowel Colour in Formantless Complex Sounds

Complex sounds were manufactured by passing the output of a buzz source through band-pass filter networks. The resulting stimuli were played both to phoneticians and to phonetically naive subjects who were asked to judge the vowel colour of the sounds. The responses showed that complex sounds are categorised consistently with regard to their vowel colour in spite of the absence of formant peaks. The following additional conclusions can be drawn: (1) The judgement of vowel colour is relatively unaffected by such features of the stimulus as variability in length between 300 and 700 msec. and the temporal qualities of the on-off transitions. (2) Vowel sounds of the back group can be simulated with a low-pass filter; and increasing the cut-off frequency shifts judgement in the direction from “high” to “low”, i.e. from /u/ to /α/, and then /a/.