Keys

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The Sound of Keys

About 10 minutes of typing of English text from a (ANY) keyboard is enough to decode what you are actually typing!!…

• Link to the directory outside the wiki.

.Wav files uploaded

• Attach:qwerty.wav

Hints and Tricks

• I noticed that the fan in Matt’s laptop is very easy to identify. Look at a period of “silence” (i.e. no key being hit) of about 1000 samples and you’ll see the super periodic wave emanating from the fan. This has several possible uses:

1. we could enhance the signal by removing the sound from the fan.
2. we could synth sound to cancel the noise from the fan while typing… (this could become a super useful app. by itself!)

Look at the output of source(“http://acccn.net/cr569/Rstuff/keys/Moby1.R”) The spline local smoother “LS” needs some tuning… I’ll look into it… These are the two plots that it produced (before the fix):

It is clear that only key5 and key6 are true hits.

OK! I fixed that problem it now works much better but it is still far from perfect. For example look at the 87th segment (output from "Ts = LS1(87)" , each segment is about 2.3 sec). The program detects 8 keys. Here is the signal around them:

Notice that all but key6 and key7 show clear hits. It looks that something is happening at key6 and key7 but it doesn’t look like a typical key hit.
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