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Encyclopedia of Psychology Alan E. Kazdin, PhD, Editor-in-Chief

AUDITORY PATTERN RECOGNITION.

Auditory perception is similar to visual perception in many important ways. Both occur in a context based on the physical properties of the source, other ongoing events in the environment, the person’s expectations, and attentional and memory constraints, as well as the nature of task. One critical factor that differs between the two is the transparency of the sound waves coming from two or more sound-producing sources. The pressure waves from every source (e.g., lawn mower, radio, and speaker) add together at each time point, so that the individual pressure wave from each source is lost in the composite. For this reason, the unique problem for auditory perception is to untangle this composite to recover the individual waves that lead to the perception of each separate source. We do hear each of the sources easily without conscious calculations, but this effortlessness belies the difficulty of the segregation into sources. In contrast, nearly all visual objects are opaque, so that the light ray from each point in space invariably comes from light reflecting off only one object.


видим разное слышим одно...

Our perceptual systems have evolved in a world that contains regularities among the vibrations creating sounds, so that we would expect that these systems should be tuned to extract those regularities.

For speech, differences between fundamental frequencies as small as 2% are sufficient to lead to the perception of two vowels or syllables, each spoken by a different voice.

Normally, the minimum difference in the onset of the components that leads to hearing more than one sound is about 50ms. In nearly all conditions, a difference in the onset time is a more important cue for segregation than a difference in offset time. Listeners do not report that they hear two sounds starting at different time points. Instead, they simply report hearing two sounds and are unable to report the order. Thus, curiously, short-time asynchronies are converted into source information and not order information.

It is important to note that the spatial position and sound quality or timbre of a sound emerges after the components have been allocated to each source. We do not hear a clarinet and a violin as separate instruments even when they are playing at the same time because the two instruments have a different quality or because they are located at different positions. Instead, we hear two because the heuristics have allocated the simultaneous components to two harmonic sources. The perceived quality and location of each instrument is the consequence of that allocation


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