Linda W. Norrix
Theodore J. Glattke
Dept. of Speech & Hear. Sci., Univ. of Arizona, Tucson, AZ 85721
An SOAE (f[sub 2]) and one XT (f[sub 1]) were used to create 2 f[sub
1]-f[sub 2] DPOAEs. External tones were applied to the ear canal at SOAE/f[sub
1] ratios between 1.08 and 1.22 XT/SOAE intensity differences varied from 0 to
approximately 50 dB SPL. DPOAE amplitude and SOAE suppression characteristics
were variable across subjects. However, the following trends were noted: (1) At
larger frequency ratios, DPOAE generation and SOAE suppression were associated
with greater XT SPLs; (2) DPOAE growth functions were characterized by slopes
<1 dB/dB, a maximum, rollover and disappearance into the noise floor; (3)
maximum DPOAEs were observed at frequencies approximately 1/2 oct below the
SOAEs; (4) DPOAE maximums were associated with a significant amount of SOAE
suppression. The results are consistent with DPOAEs created using two low-level
tones [Brown and Gaskill, in Mechanics and Biophysics of Hearing
(Springer-Verlag, Berlin, 1990)] and can be interpreted by considering
suppression in a nonlinear cochlear model [Zwicker,