Time Window
All natural sounds including animal vocalisations have distinct temporal structure consisting of individual segments with variations over time that are either slow or fast. The ability to extract, represent, and detect an acoustic feature depends on the time window used for processing the acoustic signal. A short analysis window provides higher temporal resolution while a long analysis window provides higher spectral resolution. This aspect of auditory perception is ethologically important since fast and accurate response to acoustic stimuli is critical to the survival of many animals, for instance their ability to hunt prey and avoid predators.
The optimal duration of analysis window depends upon the underlying acoustic feature that needs to be processed. A slowly varying signal requires a longer analysis window while a rapidly varying signal requires a shorter analysis window. For instance in human speech, phonemes and syllables vary different and thus require different time windows. Use of different durations of analysis windows require distinct neuronal populations with appropriate time constants. A preferred time window of a given cortical area is defined as the minimum time period required to resolve two distinct acoustic events typically using the fluctuations in the neural discharge rates of that particular area. Thus different regions of the auditory brain are employed that utilize different time windows.
In my recently published study, I set out to identify this underlying anatomical organisation of time window processing in monkeys. Next I compared this organisation in monkeys with humans which revealed interesting similarities and differences. I suggest that the differences in the auditory cortical responses could be interpreted as specialisation of the human cortex for processing of speech.
Reference:
The optimal duration of analysis window depends upon the underlying acoustic feature that needs to be processed. A slowly varying signal requires a longer analysis window while a rapidly varying signal requires a shorter analysis window. For instance in human speech, phonemes and syllables vary different and thus require different time windows. Use of different durations of analysis windows require distinct neuronal populations with appropriate time constants. A preferred time window of a given cortical area is defined as the minimum time period required to resolve two distinct acoustic events typically using the fluctuations in the neural discharge rates of that particular area. Thus different regions of the auditory brain are employed that utilize different time windows.
In my recently published study, I set out to identify this underlying anatomical organisation of time window processing in monkeys. Next I compared this organisation in monkeys with humans which revealed interesting similarities and differences. I suggest that the differences in the auditory cortical responses could be interpreted as specialisation of the human cortex for processing of speech.
Reference:
- Pradeep D, et al, "The representation of time windows in primate auditory cortex", Cerebral Cortex, 2021
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