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[AUDITORY] Localizing smoke detectors - why is it so hard?
I am writing a book for a general audience on how the brain processes
spatial information ("Making Space"). The chapter on hearing covers many
topics in sound localization, but there is one that I'm currently still
quite puzzled about: why it is so hard to localize a smoke detector when
its battery starts to fail? Here is what I have considered so far:
- To my ear, the chirp sounds high frequency enough that ILD cues should
be reasonably large.
- At the same time, it seems to have a broad enough bandwidth, and in
any case it has onset-and-offset cues, that ITD cues should be usable.
- A possibility is that the chirp is too brief, and that limits dynamic
feedback, i.e. changes in ITD and ILD as the head turns during a sound.
However, in my laboratory we have obtained excellent sound
localization performance in head-restrained monkeys and human subjects
localizing sounds that are briefer than the reaction time to make an
- An additional possibility is that we have too little experience with
such sounds to have assembled a mental template of the spectrum at the
source, so that spectral cues are of less use than is normally the case.
I'm leaning towards a combination of the last two factors, which
together would render the cone of confusion unresolved for these stimuli.
Jennifer M. Groh, Ph.D.
Department of Psychology and Neuroscience
Department of Neurobiology
Center for Cognitive Neuroscience
B203 LSRC, Box 90999
Durham, NC 27708