Production of weak elements in speech -: Evidence from Fo patterns of neutral tone in standard Chinese

Many weak elements in speech, such as schwa in English and neutral tone in Standard Chinese, are commonly assumed to be unspecified or underspecified phonologically. The surface phonetic values of these elements are assumed to derive from interpolation between the adjacent phonologically specified elements or from the spreading of the contextual phonological features. In the present study, we re-evaluate this view by investigating detailed F-0 contours of neutral-tone syllables in Standard Chinese, which are widely accepted as toneless underlyingly. We recorded sentences containing 0-3 consecutive neutral-tone syllables at two speaking rates with two focus conditions. Results of the experiment indicate that neutral-tone syllables do have a target that is independent of the surrounding tones, which is likely to be static and mid. Furthermore, the neutral tone is found to be different from the full lexical tones in the manner with which the underlying tonal target is implemented: it is slow and ineffective both in overcoming the influence of the preceding full lexical tone and in approaching its own target. Applying the recently proposed pitch target approximation model, we conclude that the neutral tone differs from the other lexical tones in Standard Chinese not only in terms of its mid target, but also in terms of the weak articulatory strength with which this target is implemented. Finally, we suggest that this new understanding is potentially applicable to other weak elements in speech.