Temporal weights in loudness : investigation of the effects of background noise and sound level

Previous research has consistently shown that for sounds varying in intensity over time, the beginning of the sound is of higher importance for the perception of loudness than later parts (primacy effect). However, in all previous studies, the target sounds were presented in quiet, and at a fixed average sound level. In the present study, temporal loudness weights for a time-varying narrowband noise were investigated in the presence of a continuous bandpass-filtered background noise and the average sound levels of the target stimuli were varied across a range of 60 dB. Pronounced primacy effects were observed in all conditions and there were no significant differences between the temporal weights observed in the conditions in quiet and in background noise. Within the conditions in background noise, there was a significant effect of the sound level on the pattern of weights, which was mainly caused by a slight trend for increased weights at the end of the sounds (“recency effect”) in the condition with lower average level. No such effect was observed for the in-quiet conditions. Taken together, the observed primacy effect is largely independent of masking as well as of sound level. Compatible with this conclusion, the observed primacy effects in quiet and in background noise can be well described by an exponential decay function using parameters based on previous studies. Simulations using a model for the partial loudness of time-varying sounds in background noise showed that the model does not predict the observed temporal loudness weights

Loudness of sounds with a subcritical bandwidth

The predicted loudness for narrowband signals with bandwidths smaller than the bandwidth of the auditory filter, i.e., with a subcritical bandwidth, depends on the type of loudnessmodel. While modelsanalyzing the long-term spectrum (stationary loudnessmodels) predict loudnesses for these subcritical signals which are independent of the bandwidth of the sound,models sensitive to the temporal structure of the signal (dynamic loudnessmodels) predict higher loudnesses for narrowband noise signals than for tones due to the inherent level fluctuations of the noise. The present study measures the loudness of subcritical sounds for center frequencies of 750, 1500, and 3000 Hz. For all three center frequencies, the level of the narrowband noise had to be up to 5 dB higher than the level of the equally-loud tone at the center frequency. This experimental finding is at odds with both predictions, i.e., the loudness is neither the same for all signals nor is the level of the narrowband noise smaller than that of the equally-loud tone. The data indicate a special character of sounds with a distinct tonal character which is not accounted for in current loudnessmodels

Temporal weights in loudness: Investigation of the effects of background noise and sound level.

Previous research has consistently shown that for sounds varying in intensity over time, the beginning of the sound is of higher importance for the perception of loudness than later parts (primacy effect). However, in all previous studies, the target sounds were presented in quiet, and at a fixed average sound level. In the present study, temporal loudness weights for a time-varying narrowband noise were investigated in the presence of a continuous bandpass-filtered background noise and the average sound levels of the target stimuli were varied across a range of 60 dB. Pronounced primacy effects were observed in all conditions and there were no significant differences between the temporal weights observed in the conditions in quiet and in background noise. Within the conditions in background noise, there was a significant effect of the sound level on the pattern of weights, which was mainly caused by a slight trend for increased weights at the end of the sounds ("recency effect") in the condition with lower average level. No such effect was observed for the in-quiet conditions. Taken together, the observed primacy effect is largely independent of masking as well as of sound level. Compatible with this conclusion, the observed primacy effects in quiet and in background noise can be well described by an exponential decay function using parameters based on previous studies. Simulations using a model for the partial loudness of time-varying sounds in background noise showed that the model does not predict the observed temporal loudness weights