CONTRALATERAL SUPPRESSION OF DISTORTION PRODUCT OTOACOUSTIC EMISSION IN HUMANS

The distortion product otoacoustic emission (DPOAE) was measured for 10 normal-hearing subjects without and with presentation of contralateral broad-band noise stimulation. DPOAE data were obtained for a wide frequency range of primary tones (1.4- 9 kHz), two intensity levels of primary tones (L1=60 dB SPL; L2=50 dB SPL and L1=70 dB SPL; L2=60 dB SPL) and three intensity levels (50, 60 and 80 dB SPL) of contralateral stimulus. The experimental results indicated that the degree of DPOAE suppression depended on the frequency of the primary tones and the level of the contralateral noise stimulation. In the low frequency range (1.4 – 2.5 kHz) of the primary tones, contralateral stimulation reduced the DP level more than in the middle frequency range (2.5- 5 kHz). In the highest frequency range tested (above 5 kHz), the suppression effect was within the limit of SD. Generally the higher the contralateral noise level the higher the suppression