Modulation threshold functions for chronically impaired Menière patients.

Detection thresholds for sinusoidally amplitude-modulated broad-band noise were measured as a function of modulation frequency for both ears of 6 chronic Menière patients who suffered unilateral hearing impairments. Modulation thresholds were measured with an adaptive cued-standard forced-choice psychophysical method. Better-ear modulation thresholds were similar to normative data previously reported [Formby, C.: J. acoust. Soc.Am. 78:70-77, 1985], whereas 5 of the 6 patients exhibited deficits in modulation detection with their poorer ears. Modulation thresholds averaged across the patients' poorer ears were similar to the normative thresholds through 60-100 Hz; at higher modulation frequencies, sensitivity declined at approximately twice the normal attenuation rate (i.e., 6 vs. 3 dB per octave). The poorer-ear data can be described by the mathematical representation for a simple low-pass filter with a cutoff frequency of 60 Hz. This pattern of the Menière modulation thresholds is consistent with broadened peripheral tuning due to hydrops.