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In lugnet.robotics, Claude Baumann wrote:
> We've worked some hours to do some interesting experiments with the NXT sound
> sensor in order to learn more about the sensor characteristics:
>
> Please consult: http://www.convict.lu/Jeunes/RoboticsIntro.htm
Very nice. I'll have to dig through it again in detail, but I didn't find
anything interesting at 3 kHz... perhaps because I didn't go that high (oops).
To figure out the frequency response I did it manually: I borrowed a signal
generator and speaker from the university, as well as a sound meter, and then
simple manually cranked up the frequencies on the signal generator, noting what
readings the sound sensor returned in dB and dBA mode, as well as the dB level
displayed on the meter. The summarized results (over a lower range of
frequencies) are here:
http://www.brickshelf.com/cgi-bin/gallery.cgi?i=3348152
My conclusion was the sensor can be used to distinguish fairly pure tones below
roughly 1 kHz (below 1 kHz, there's a nice distinguishable difference between dB
and dBA modes), but not above that. I didn't go up to very high frequencies,
because among other things I was originally trying to get one NXT to distinuish
the tones played by an NXT or RCX, the the sound production at very high
frequencies with the sources is very weak.
More annoying, although I can get an NXT to reliably detect *pure* tones in the
proper range ("is this tone above or below 1 kHz?"), it seemed hopeless for
"normal" sounds that are really a very messy combination of waveforms. In other
words, having one NXT "listen" to another just didn't work out well.
Using the DSP module is a very nice way to do this, by the way. I'll have to dig
through this some more.
--
Brian Davis
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Message has 1 Reply:
 | | Re: NXT sound sensor characteristics
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| Thanks Brian (...) Your excellent graph shows that you tried to maintain the sound pressure constant. We did the inverse in the last graphs, where we tried to draw the curve for a constant NXT sensor value. We also repeated the experiment, and this (...) (15 years ago, 28-Feb-09, to lugnet.robotics, lugnet.boats)
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Message is in Reply To:
| | NXT sound sensor characteristics
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| We've worked some hours to do some interesting experiments with the NXT sound sensor in order to learn more about the sensor characteristics: Please consult: (URL) and help discussing. Claude Baumann (15 years ago, 27-Feb-09, to lugnet.robotics)
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