EFFECT OF LOW-FREQUENCY GAIN REDUCTION ON SPEECH RECOGNITION AND ITS RELATION TO UPWARD SPREAD OF MASKING

Speech recognition was measured in listeners with normal hearing and i n listeners with sensorineural hearing loss under conditions that simu lated hearing aid processing in a low-pass and speech-shaped backgroun d noise. Differing amounts of low-frequency gain reduction were applie d during a high-frequency monosyllable test and a sentence level test to simulate the Frequency responses of some commercial hearing aids. T he results showed an improvement in speech recognition with low-freque ncy gain reduction in the low-pass noise, but not in the speech-shaped background noise. Masking patterns also were obtained with the two ba ckground noises at 70 and 80 dB SPL to compare with the speech results . There was no correlation observed between the masking results and th e improvement in speech recognition with low-Frequency gain reduction.