Ear dominance in dichotic chords and frequency discrimination in the right and left ear

Abstract

In a series of experiments frequency discrimination thresholds were determinined for pure tones presented either to the right or to the left ear of experienced listeners. In some conditions the stimulus was monaural, whereas in others a tone of different frequency was simultaneously present in the contralateral ear. The difference between the frequency of the target in the discrimination task and that of the contralateral tone was 4–6%. Center frequencies of 1.2, 1.7, and 3.2 kHz were investigated. Results indicate that there is a small but reliable discrepancy between just-noticeable frequency differences obtained for the right and for the left ear, both in the monaural and in the dichotic conditions. Furthermore, the direction and the degree of asymmetry with respect to the frequency resolving power of the two ears was found to be strongly correlated with the direction and the degree of ear dominance for the pitch of dichotic two-tone complexes [see Efron and Yund, J. Acoust. Soc. Am. 59, 889–906 (1976)]. In other words, for a given subject and in a given frequency region, the ear which was more efficient in the frequency discrimination task was also the one which dominated the pitch percept of a dichotic tone pair in the same frequency region. Implications of the relationship between the two types of functional asymmetry of the auditory system are discussed in the paper.