Masking by Complex Sounds
Psychoacoustic studies have well established the principle
relations that determine masked threshold for a sinusoidal
signal in the presence of simple maskers such as single
sinusoids or
bands of noise. Can what we have learned from these studies
be used to predict masking by sounds of much greater
complexity? More complex maskers can, of course, be constructed by
combining single tones or bands of noise. According
to the auditory filter (critical band) model, the amount
of masking produced by such combinations should equal the sum
of the masking produced by each masker when presented alone. For
example, if two maskers A and B produced the same amount of masking
when presented alone, they should produce twice as much
(3 dB more) masking when presented together. The figure below
shows the results of combining two equally effective maskers. The
amount of masking produced by the combination far exceeds the
amount of masking predicted by the auditory filter model. We'll
have more to say about this in class.
