Effect of noise bandwidth on the loudness of a 1000-Hz tone

The loudness of a 1000-Hz tone was measured by the method of adjustment in the presence of bands of white noise that varied in width from critical to very broad. Comparisons were made between the effects on loudness of noise bands set at nearly the same over-all sound-pressure level (SPL) and between the effects of those adjusted to produce the same amount of masking at threshold. The results suggest that, as long as the threshold shift is maintained constant, the loudness of the tone below an SPL of about 30 dB is reduced equally by narrow- and wide-band noise. At higher SPLs, the loudness of the tone tends to grow more rapidly in the presence of a narrow-band noise than in the presence of a wide-band noise. The magnitude of the effect depends on the width of the noise band.