INFLUENCE OF CONTRALATERAL NOISE ON AUDITORY INTENSITY DISCRIMINATION

Auditory intensity discrimination at 2000 Hz was determined for the left and right ears of normal listeners at intensity levels of 23 to 78 dB sound pressure level (SPL) in the presence of contralateral white noise and sawtooth noise from quiet to 63 dB SPL. It was hypothesized that contralateral noise might affect the left temporal lobe in a manner analogous to left temporal excision, resulting in improved intensity discrimination only in the left ear. Results showed that intensity discrimination was significantly improved in both ears by contralateral noise for subjects receiving test tones of 38 dB and above. Contralateral noise did not improve intensity discrimination in subjects who received test tones of 38 dB and below, but the difference limens for the left ear were significantly smaller in both quiet and noise. The original hypothesis was not upheld, and further study of the limiting conditions for the enhancement of differential sensitivity by contralateral noise is suggested. The finding of left ear superiority for lower level test tones is discussed in relation to right hemisphere dominance for nonverbal stimuli. © 1969, Acoustical Society of America. All rights reserved.