Human echolocation : The effect of object size, distance and auditory angle
Both blind and sighted persons may use echoes for detecting objects.
The effect of object size on echolocation was tested in a listening
experiment with 15 sighted participants. Noise burst of 500-ms were
generated and recorded in an ordinary room, with and without a
reflecting object. The diameter of the reflecting object was 0.25 or
0.50 m, and it was located at a distance of 0.5, 1, 2, 3 m from the
microphones. Pairs of sounds, one with and one without the object,
were presented to the listeners. Their task was to decide which of the
two sounds that were recorded with the reflecting object. The results
showed that it was harder to detect the 0.25 than the 0.5 m object, and
that performance generally decreased with distance. The auditory
angle, which is a function of the size to distance ratio, was found to
predict detection performance fairly well.
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