>Ray Dillinger wrote:
>>
>> If you get two sensitive microphones in a room, you
>> should be able to do interferometry to get the exact locations
>> on a keyboard of keystrokes from the sound of someone typing.
>> I guess three would be better, but with some reasonable
>> assumptions about keys being coplanar or on a surface of known
>> curvature, two would do it. Interesting possibilities.
>>
>> Bear
>>
>> [A quick contemplation of the wavelength of the sounds in question
>> would put an end to that speculation I suspect. --Perry]
We hear low-frequency sounds when we type. But have we ever checked
for high-frequency sounds outside of human hearing range? I'd bet
a keyboard has a number of squeaks and ticks and twangs up there.
I'd also bet that most of the keys, after a keyboard's broken in,
don't sound exactly alike -- wear and tear, typing patterns, etc.
You might be able to resolve ambiguities of interferometry by using
the sounds of the keys themselves.
Bear
