Loudness of ramped and damped sounds that are temporally shifted across ears

摘要

In a previous study we have shown that amplitude-modulated sounds are louder when their modulation is out of phase across the two ears than when it is in phase. The level difference required for equal loudness (LDEL) of sounds with diotic presentation and an interaural modulation phase difference of 180° was about 2 dB. This could be explained by a loudness model where binaural summation lags behind binaural inhibition. The present study investigated the binaural loudness of ramped and damped sounds in a similar manner. Stimuli consisted of trains of 1000-Hz tone pulses with linear rise and fall times with ratios of 1:10 (damped sounds) or 10:1 (ramped sounds). Stimuli contained 28 55-ms pulses, 14 110-ms pulses or 7 220-ms pulses, resulting in a stimulus duration of 1540 ms plus half the pulse duration for the interaurally shifted stimuli. The LDEL between diotic and interaurally shifted stimuli was close to 0 dB for all of these conditions. For a single 220-ms pulse, the LDEL was 1.4 dB for damped sounds, and 3.0 dB for ramped sounds, the diotic sounds being louder. The difference between a single pulse and a pulse train suggests differences between short-term and long-term loudness judgments.