Critical masking bands for sensorineural tinnitus.

The level of noise required to mask tinnitus was measured in 12 subjects with sensorineural tinnitus; the noise was centred on the estimated pitch of the tinnitus, and the overall level required to just mask the tinnitus was measured for masker bandwidths of 2.5, 10, 20, 30 and 50% of the noise centre-frequency. For four of the tinnitus subjects, masking functions were similar to those observed in normal-hearing subjects with a "simulated" tinnitus (15-dB Sensation Level, 4-kHz pure tone). The other eight tinnitus subjects, however, required masking levels that were either independent of masker bandwidth or showed anomalous changes in masker level as bandwidth was increased. These results suggest that certain masker bandwidths can be more efficient than others for the masking of tinnitus, and that masker characteristics deserve close attention in the design and fitting of tinnitus-masker instruments.