Individual differences in the masking level difference (MLD) with a narrowband masker at 500 or 2000 Hz

Abstract

The MLD for a narrowband masker is associated with marked individual differences. This study examines factors that might account for these individual differences, including binaural temporal resolution and sensitivity to interaural cues based on time or level. MLD data were collected for 50-Hz wide maskers at 500 and 2000 Hz, gated on for 400-ms. The signal was a pure tone at the center frequency of the masker, of either brief (15-ms) or long (200-ms) duration. Brief signals were coincident with either a local minimum or maximum in the pattern of inherent amplitude modulation. Sensitivity to interaural time and level cues was assessed using similar stimuli, with the exception that the long-duration signal was a 50-Hz band of noise, generated to provide just interaural time cues, just interaural level cues, or both types of cues. Binaural temporal windows were estimated based on pure tone detection thresholds for a brief 500-Hz tone presented at different points in time relative to an abrupt interaural phase transition in a masking noise, bandpass filtered between 100 and 2000 Hz. Relationships between MLD results and those of binaural temporal windows and interaural cues of time and level will be discussed.