ASA 125th Meeting Ottawa 1993 May

3aMU7. Monotic and dichotic modulation detection interference.

Jane M. Opie

Sid P. Bacon

Psychoacoust. Lab., Dept. of Speech and Hear. Sci., Arizona State Univ., Tempe, AZ 85287-1908

Monotic and dichotic modulation detection interference was measured for both practiced and naive subjects who listened to either all monotic or all dichotic conditions first. Subjects detected 10-Hz amplitude modulation of a 1-kHz target tone in the presence of a 4-kHz masker that was either unmodulated or modulated from 2 to 80 Hz at a depth of 100%. The target and masker were presented for 500 ms at a level of 60 dB SPL. Both practiced and naive subjects demonstrated less interference when the masker was presented to the ear opposite the target. On average, the maximum amount of interference was approximately 4 dB in the dichotic condition and approximately 7 dB in the monotic condition. In addition, the tuning for modulation detection was similar for the dichotic and monotic conditions, with the greatest interference observed for masker modulation frequencies that were the same as or similar to the target modulation frequency. [Work supported by NIH.]