SPECTROTEMPORAL DESCRIPTION OF DIPHTHONGS IN F1-F2-F3 SPACE
The prevailing approach to the acoustic-phonetic description of the diphthong is based (1) on the two lowest, vocal-tract resonance (or formant) frequencies (F1 and F2) considered either individually or jointly in the F1-F2 plane, and (2) on a very sparse representation of the temporal course of these frequencies. While this time-honoured approach has been particularly useful for characterising the initial and final vowels of the diphthong, there appears to be very little progress beyond the F1-F2 plane, as a parametric framework for elucidating the dynamic nature of the vowel-to-vowel transition. By contrast, a more accurate spectro-temporal description of a subset of the Australian English diphthongs (/aI/ and /I/) is obtained in this work by considering a detailed, temporal representation of the three lowest formant-frequencies (F1, F2 and F3). In particular, certain nonlinearity features of the densely-sampled contour of the F3 are highlighted, which appear to have hitherto been either unknown or considered inconsequential to the specification of the diphthong. This finding is shown to contribute a new, three-dimensional (F1-F2-F3) perspective on the acoustic characteristics of the vocalic transition of the diphthong.
diphthong australian english acoustic phonetics formant contours formant space diphthong surface vowel surface