The past few days have been spent hunkered over a table in the pComp lab, trying to find a way to get the simple sound monitor prototype up and running — and I think I’m finally there. Or, at least, I’ve got a start. I’ve ordered some new parts, which I have to try out and mess around with, mostly mics. All mics, as it turns out, were not created equal.
I started with ye olde Radioshack PC Board condenser mic:
And eventually (mostly due to the pre-soldiered-ness and a slightly more attentive range) ended up with this guy, another Radioshack electet:
I was lucky enough to have some suggestions to check out the ITP Sensor Wiki, and found some fantastic schematics from SoYoung Park and code from Jeff Gray (thanks!!), which after some tweaking and testing brought me to this:
This is a Processing app that watches the incoming analog values from the Arduino (in this case, the audio signal), and outputs the points on the screen, moving from left to right. The red dots are the actual values, and the line is the average. For my purposes, this works splendidly, as mics output both positive and negative voltage — so in this case, with the signal coming out of the mic boosted 2.5v, watching for the average gets a really good picture of what’s going on.
This is the ambient room volume in the pComp lab:
And this is what happens when you clap a few inches away from the mic a few times:
The circuit is based off of the one Tom Igoe has in the Physical Computing book, with SoYoung’s rectifier and low-pass filter added in, the guts of which look like this:
And the whole thing like this:
So here, with better feedback examples, there’s this:
In this case, when you make a loud enough noise close enough to the mic (that blurry thing in the center), the big ol’ green LED in the upper-right corner of the breadboard gets tripped and goes fully bright. It’s actually a pretty engaging interaction — I’ll have to take video and post that shortly.
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