Index of content:
Volume 134, Issue 6, December 2013
- SPEECH PRODUCTION 
134(2013); http://dx.doi.org/10.1121/1.4824930View Description Hide Description
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.
134(2013); http://dx.doi.org/10.1121/1.4828834View Description Hide Description
This study examined how, in repetitive speech, articulatory movements differ in degree of variability and movement range depending on articulatory constraints manipulated by phonetic context and type of CVC-CVC word pair. These pairs consisted of words that either differed in onset consonants but shared rhymes, or were identical. Articulatory constraints were manipulated by employing different combinations of vowels and consonants. The word pairs were produced in a repetitive speech task at a normal and fast speaking rate. Articulatory movements were measured with 3D electro-magnetic articulography. As measures of variability, median movement ranges and the coefficient of variation of target and non-target articulators were determined. To assess possible biomechanical constraints, correlation values between target and simultaneous non-target articulators were calculated as well. The results revealed that word pairs with different onsets had larger movement ranges than word pairs with identical onsets. In identical word pairs, the coefficient of variation showed higher values in the second than in the first word. This difference was not present in the alternating onset word pairs. For both types of word pairs, higher speaking rates showed higher correlations between target and non-target articulators than lower speaking rates, suggesting stronger biomechanical constraints for the former condition.