A Perceptual Study of Mandarin Tones 2 and 3

Due to their similar concave shapes, Tones 2 and 3 are said to be the most confusable pair in Mandarin, and no reliable perceptual cues have been found. The purpose of this perceptual study was to find (1) the perceptual cues for discriminating these two tones, and (2) the possible causes of listeners' misidentifications. Experiment 1 was designed to test the hypothesis that the timing of the turning point may constitute a perceptual cue. Two fundamental frequency continua were superimposed on the syllable [wu] and the location of the turning point was manipulated in each. A binary forced-choice identification test was given to Mandarin listeners. The results show that the distinction between Tones 2 and 3 is cued by the timing of the turning point, which is correlated with the degree of the initial fall. In Experiment 2, ten minimal pairs of Tones 2 and 3 spoken by four native speakers were presented to Mandarin listeners for labeling. Acoustic analysis of the mis-labeled tokens indicates that mistakes occurred when the correlation between the timing of the turning point and the degree of the initial fall was violated.