Time-varying partial loudness of noise burst sequences in stationary noise with a similar level

Loudness increases with increasing duration up to 200 ms after sound onset. This temporal integration is well documented in quiet but less understood in the presence of other sounds and for very short durations. The present study investigates the temporal integration of partial loudness for bursts of noise in the presence of equally intense background noise. Level differences required for equal loudness between a reference burst duration of 20 ms and target burst durations of 1, 2, 5, and 10 ms were obtained using a 1-up/1-down staircase procedure in the laboratory and online for burst repetition rates of 5, 10, and 20 Hz and for rectangular and Hann shaped bursts. All results showed that the short duration bursts were perceived as louder than expected from the temporal integration of energy. The difference was equivalent to a change in level up to 6.7 dB and was larger for higher burst repetition rates. The difference was higher when using abrupt onsets and offsets for both target and reference compared to bursts with a Hann window shape. Differences between experiments conducted in the laboratory and online were small (up to 1.2 dB) but were statistically significant.