Modulation detection interference in listeners with cochlear hearing loss: Effect of modulation depth and onset delay.

Abstract

Modulation detection interference (MDI) was measured for listeners with normal hearing (NH) and cochlear hearing loss (HI). The signal was 1 kHz, and the interferer was 2 kHz. The stimuli level was 50 or 22 dB SL. The interferer was modulated with 8 Hz at various modulation depths (25, 50, 75, or 100%). The onset of signal was delayed by 0, 125, 250, 375, 500 or 625 ms relative to onset of the interferer. For NH subjects, MDI increased systematically with increasing modulation depth of the interferer. MDI almost disappeared with 375 or 500 ms onset delay except a condition with the interferer of 25% modulation depth where there was no MDI at all across different onset delay conditions. In contrast, for HI subjects, there was quite an amount of MDI even with the interferer of 25% modulation depth, and MDI was greater than NH for all modulation depths at 0 and 125 ms onset delays, suggesting that the perceived modulation depth of the interferer might be exaggerated for HI than for NH.