Preliminary Measurements of Binaural Masking-Level Difference When Using Hearing Aids for Sensorineural Hearing Loss

The Binaural Masking-Level Difference phenomenon occurs both in listeners with normal hearing and with sensorineural hearing loss (SNHL). Previous studies of BMLDs involving SNHL listeners used a 500- or 2000-Hz pure tone as the target signal, but the BMLD performance of SNHL listeners with stimulus amplified for other frequencies has not been reported previously. Therefore, this study aimed to measure the BMLD in SNHL listeners at various frequencies after amplification by hearing aids. Thirty subjects with mild to moderately severe SNHL participated in the experiments. The BMLDs were measured based on the detection threshold differences for pure tones of 125, 250, 500, 1000, and 2000 Hz in the presence of white noise when presented interaurally in phase (S₀N₀) and interaurally in antiphase (S_πN₀). The results show that when using white noise as a masker, the average detection thresholds for the target signals were significantly lower in the S_πN₀ condition compared to those in the S₀N₀ condition (p < 0.001). The SNHL subjects had mean BMLDs of 2.3, 4.8, 4.7, 4.2, and 3.7 dB at 125, 250, 500, 1000, and 2000 Hz, respectively. The results obtained in the present study provide preliminary support that SNHL listeners hear target signals easier in noisy environments when the signals are amplified by hearing aids and presented in antiphase.