The influence of signal duration, signal frequency and masker duration on binaural masking level differences

Binaural masked thresholds were measured to study the influence of masker and test signal duration on binaural unmasking for three different interaural phase relations (N0S0, N0S pi and N pi S0) and for test signal frequencies ranging from 200 to 800 Hz. Six observers participated in this study. An adaptive 3 Interval Forced Choice paradigm was employed. Reducing the signal duration from 250 to 20 ms results in an average binaural masking level difference (BMLD) increase of 2.5 dB for all frequencies and both dichotic conditions. Masker duration, however, has a more distinct influence on BMLD: a decrease from 500 to 25 ms reduces the BMLD in the N0S pi condition by 7 dB and in the N pi S0 condition up to 11 dB at low frequencies. These results reveal further evidence for different detection mechanisms in monaural and binaural masking experiments.