Auditory spectral integration in the perception of diphthongal vowels

This study considers an operation of an auditory spectral integration process which may be involved in perceiving dynamic time-varying changes in speech found in diphthongs and glide-type transitions. Does the auditory system need explicit vowel formants to track the dynamic changes over time? Listeners classified diphthongs on the basis of a moving center of gravity (COG) brought about by changing intensity ratio of static spectral components instead of changing an F2. Listeners were unable to detect COG movement only when the F2 change was small (160 Hz) or when the separation between the static components was large (4.95 bark).