Factors affecting the Mandarin dichotic digits test

Objective: Data with regard to the Mandarin dichotic digits test (DDT) are limited, with conflicting results reported between the Mandarin and English DDTs. The current study examined factors that might affect the performance in the Mandarin DDT. Design: The digits were arranged in 3 sets of 20 dichotic pairs; each set comprised 2, 3 or 4 digits in a pair. Study sample: Forty-one young, native Mandarin speakers with normal hearing were tested; 30 of them were right-handed and 11 left-handed. Six participants repeated the test. Results: The prevalence of ceiling effect in recognition score decreased systematically as the digit-pair length increased. At digit sets of 3-pair and 4-pair, the right-handed group showed a significant higher recognition score at right ear than left ear, while the left-handed group reversed the performance. The score difference between ears is significantly different between the right- and left-handed groups. The retest of the Mandarin DDT was reliable. Conclusions: For the right-handed group, a right-ear advantage can exist in the Mandarin DDT at a longer digit-pair length, similar to what was reported in the English DDT. Moreover, for the left-handed group, the attended right hemisphere in processing the tonal digits can result in a left-ear advantage.