Low-level segmental and suprasegmental phonetic complexity in typical and atypical speech (1/4)

Johan Verhoeven (City University of London)
Intrinsic Vowel Pitchː Physiological Determination or Perceptual Enhancement?

Intrinsic vowel pitch refers to the phenomenon that high vowels such as /i/ and /u/ in languages of the world have a significantly higher fundamental frequency than low vowels such as /ɑ/ and /a/. This phenomenon has been attested in every language that has been investigated for it (Whalen & Levitt, 1995, Van Hoof & Verhoeven, 2011). This exact value of this F0 difference between high and low vowels differs substantially from as small as 7 Hz in Arabic to as large as 28 Hz in Dutch and English (Van Hoof & Verhoeven, 2011).

Intrinsic Vowel Pitch has been accounted for in essentially two ways. On the one hand, there is the assumption that IF0 is entirely physiologically determined by the interaction between the articulatory and phonatory systems in speech production. This hypothesis holds that IF0 determined by articulation and cannot be actively controlled by speakers. On the other hand, there is the hypothesis, which holds that IF0 does play a communicative role in languages in that it is used by speakers to perceptually enhance vowel contrasts, which is particularly useful in languages with large vowel systems. This debate between the two hypotheses has been going on for decades and has not been resolved as yet.

This lecture will review some of the arguments for both hypotheses and presents evidence for the perceptual enhancement hypothesis on the basis of a large number of acoustic measurements of the vowels in the speech of children with hearing impairment and those with normal hearing. These measurements indicate that it may be worthwhile to explore the role of hearing in IF0 and a case will be presented for the communicative value of IF0.