| The loudness of quasi continuous impulse noise has been studied as a function of impulse duration and repetition rate, and the spectral shape and relative level of steady background noise. The measurements were performed on 1-second trains of white-noise bursts with exponentially decaying envelopes. The repetition rates were 5 to 100 Hz. The impulse durations were adjusted so that the duty factor of the impulse train (product of the repetition rate and the effective duration of the impulses) varied from 0.025 to 0.1. Steady white background noise was added at peak-to-background ratios of 10, 20 and 30 dB. The loudness levels of the stimuli relative to a steady white noise reference stimulus at a presentation level of 60.5 dB L;Under most conditions, the loudness levels of the quasi continuous impulse noise stimuli were best predicted by the equivalent sound pressure level, L;In the second experiment, the spectral shape of the background noise did not significantly affect the point of subjective equality. However, there was a significant interaction between background noise spectrum and peak-to-background noise ratio which was suggestive of a masking process. |
