
As an added bonus, the PS3 Eye has a built-in 4-channel microphone array. It is apparently used for adaptive noise cancelling.
Out of curiousity I decided to see if the drivers would allow capturing 4-channel audio from the microphone array. I was pleasantly surprised to find that Audacity was able to record using the default USB ALSA drivers.
I measured the distance between the outermost microphones to be about 62mm. At an air temperature of 20°c that corresponds to (0.062/343)=0.00018s or about 180μs delay between channel 1 and 4.
Holding the PS3 Eye almost side-on and making a "tick" sound:
The two middle channels were reversed, however after flipping them the waveforms clearly show a delay between successive channels, and also a reduction of amplitude to the most distance microphone. It is what you'd expect, but still neat!
The highlighted selection above marks the zero-crossing for the second oscillation. Measuring the delay between the zero-crossings at several locations gave ~8 samples delay between channel 1 and 4.
At 44.1kHz, that is (8/44100) ~ 181.4μs or about 62.2mm separation. Thats close enough for me!
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