Audacity Forum

I'm doing what my adviser at school says is possible-record one track of a stereo through a mike and the other with a set of electrodes measuring vocal activity. The device which is feeding the sound to the computer is an edirol ua- 25. The mike plug directly into that. The electrode goes in to a glottal enterprises machine and a plug comes out of that and into the right track on the edirol. I can get a signal from both at the same time, however the audio is terribly noisy with what sounds like interference. When I don't use the electrodes and still have the glottal enterprises machine on, but the electrodes no where near, I get a clean signal. When I unplug the mike I get audio through the 2nd, right channel which means that the electrodes are picking up some audio. Is there a way to make one track of a stereo audio and one something else, and if so, what should that signal be to get EGG readings? These need to be recorded at the same time, so two mono tracks doesn't seem to be an option, and I'm not sure how to change the routing in the edirol to enable that anyway. Thanks- Carol

There's not quite enough here to nail down a solution.

Leave the scientific machine off and disconnected. Plug the microphone into one Edirol connection and leave the other unconnected. Make a brief voice recording and then stop talking and then stop the recording. Export as a stereo WAV file.

Now do the whole thing again with the microphone plugged into the other side. We're talking six second recordings, here, not Hamlet.

Export that as a stereo WAV file. Load each file and see if there's anything on the "blank" channel. Is there anything leaking from the active microphone channel to the dead one? You may need to split the stereo channel up into individual mono channels and mute the live one. I'm expecting a 40dB or 50dB separation between the two channels. That's considered good to excellent.

If this test works, then the microphone and Edirol are working correctly and the scientific equipment is Doing Something Wrong -- either overloading the Edirol or providing signals on the "wrong" wires, or doing something else really naughty.

Koz