Strange Buzzing on Recording for One Track

I’ve been recording with audacity for a short while and it’s usually worked fine, but I’ve had an issue arise a couple times.

Firstly, I’m using Mac OSX Mountain Lion, 10.9.5. I’m using audacity 2.0.3, and I can’t remember if I installed it from the dmg or from a zip.

Anyways, recording on three tracks with three separate mics, looks something like this. At some point along the recording, something happens, the bottom track now sounds like he was speaking through a fan; there’s a weird echo, a digitized echo of his voice. The track now looks like this. This happened halfway through, and there continued to the end.

I have no idea why this happened. It happened before, but it started at the beginning of the track. Is it a problem with the mic, or is this some problem I’m causing somehow? Is there a way to avoid this?

Thanks a lot in advance.

recording on three tracks with three separate mics

You must be leaving words out or something because you can’t do that. Audacity will only record from one device at a time. The illustration says you 're recording from the Built-In Microphone. Where are the three tracks coming from?


Sorry, the image isn’t from a current recording. On mac, I create an aggregate device to accept input from the separate mics, but it’s set as one device. Done with Audio MIDI setup.

Sorry, the image isn’t from a current recording.

We can only go with what you tell us.

I create an aggregate device

I’ve done that with two microphones, but never three.

I got nothing. If somebody said I had to guess at it, I’d say the machine wasn’t powerful enough to handle it. Do you have an SSD instead of a spinning metal drive? Serious memory and USB3? Live audio streams are rough and juggling three of them at the same time is likely to cause problems. USB is a timeshare system. It’s not like FireWire.

For one example, you can’t run a USB microphone through a USB hub with a keyboard and mouse. The sharing will cause digital trash in the sound.


I’ll have to assume something like this is happening for now. Thanks a lot for your help.