Articulatory limit and extreme segmental reduction in Taiwan Mandarin

The present study investigated whether extreme phonetic reduction could result from acute time pressure, i.e., when a segment is given less articulation time than its minimum duration, as defined by Klatt [(1973). J. Acoust. Soc. Am. 54, 1102-1104]. Taiwan Mandarin was examined for its known high frequency of extreme reduction. Native speakers produced sentences containing nonsense disyllabic words with varying phonetic structures at different speech rates. High frequency words from spontaneous speech corpora were also examined for severe reduction. Results show that extreme reduction occurs frequently in nonsense words whenever local speech rate is roughly doubled from normal speech rate. The mean duration at which extreme reduction begins occurring is consistent with previously reported minimum segmental duration, maximum repetition rate and the rate of fast speech at which intelligibility is significantly reduced. Further examination of formant peak velocities as a function of formant displacement from both laboratory and corpus data shows that articulatory strength is not decreased during reduction. It is concluded that extreme reduction is not a feature unique only to high frequency words or casual speech, but a severe form of undershoot that occurs whenever time pressure is too great to allow the minimum execution of the required articulatory movement.