Perceptual Coherence : Hearing and Seeing

In sum, the masking release is greatest when the bands are perceived to
form one (or more) noise sources based on the onset synchrony of noise
bands with the same amplitude modulation envelopes. This really does
not tell us why it is easier to detect the tonal target. It might simply be that
the tone is more easily heard in the amplitude dips of the noise bands. If the
two noise bands are comodulated, the sum has distinct intervals in which
the masking noise is very weak. But if the noise bands are uncorrelated, the
sum does not have such distinct intervals of low intensity. However, a dip
explanation does not explain why onset asynchrony affects the size of the
release.
Summary
Gain Control and External and Internal Noise 291
At least two major issues have been covered here. First, how does noise,
both internal and external, affect detection and identification performance?
Second, how does the nervous system compensate for the limited firing
range of individual receptors in the face of the enormous range of environmental
input?
The material presented here reinforces the contentions presented in
chapter 1 that perceiving is inherently contextual and depends on processes
at both multiple spatial and temporal time scales. The effect of noise and
the processes underlying gain control depend on the specifics of the actual
stimulus presented and its internal correlational structure and temporal
variation, as well as the context of the experiment and the statistics of the
natural world. It is tempting to conceptualize the resulting efficiency in
terms of maximizing information transmission.