Ning-ji He
Richard A. Schmiedt
Dept. of Otolaryngol. and Commun. Sci., Medical Univ. of South Carolina, 171 Ashley Ave., Charleston, SC 29425-2242
The fine structure of the 2f[sub 1]-f[sub 2] acoustic distortion product
(ADP) was measured in a group of normal-hearing subjects with different
combinations of primary levels (L1 and L2). The frequency ratio (f[sub 2]/f[sub
1],f[sub 2]>f[sub 1]) was 1.2, and the f[sub 2] frequency was swept from 1781
to 2300 Hz in 1/32 octave steps. In condition 1, L1 was fixed at 50 dB SPL
while L2 varied from 30 to 75 dB SPL in 5-dB steps. In condition 2, L2 was
fixed at 50 dB SPL and L1 was varied as in condition 1. For a fixed L1, an
upward frequency shift was evident in the ADP fine structure as the L2 level
increased, whereas for fixed L2, a downward frequency shift in the ADP pattern
was observable with an increasing L1. These results support a vector sum
computer model for the ADP fine structure [Sun et al.,