Permuted (?) blocks of input exactly 10 ms long, HELP!!!

Was using Audacity 2.0.2 and a Blue Snowball happily since November for voice recording. Windows 7.

Problem started suddenly just two days ago:

Record a clip, and the input has many blocks exactly 441 samples (10 ms) long where the signal is wrong, and apparently “time-travelled” from just a bit earlier or later (not sure which). The stretches of good signal in between seem also to be multiples of 10 ms.

I try saying “fafafafa” making a vowel and sibilant with very different waveforms. I see bits of each mixed in with the other. Not as if the mic simply cuts out – seems like buffering gets confused somewhere and permutes blocks of 10 ms.

Has anyone seen similar?

Remedies tried without success: (1) connect mic directly to different USB port – it had been going through a hub. (2) Upgrade 2.0.2 to 2.0.3. (3) Restart computer, uninstall Audacity (2.0.3), reinstall it.

Edit > Preferences, choose “Recording” on the left and make sure “Audio to buffer” is at least 100 milliseconds.

Turn off Transport > Software Playthrough unless you need it.

Are you append-recording to the end of the same track? If so this could be a bug (turn Transport > Overdub off and it should stop happening).


Latency was exactly 100, Overdub was on, Playthrough was off. I will try without Overdub.

Would higher latency be helpful?

What about Latency Correction? It is -130.

Any clue why this might have started with little warning after long use with no problem?

Problem seemed to happen more often when I had one track, muted, and recorded to another new track.

Problem seems to be intermittent, and affects a new recorded clip a lot, or not at all. But I have not yet attempted to record clips of more than tens of seconds since I saw this.

Are there other tricks, like changing the priority or CPU affinity of certain processes?

Preliminary trials without overdub seem to work. I suppose I could try 200 ms latency if I have more trouble?

I think the problem was more likely when recording with another existing track, even if that one was muted.

“Latency correction” is only a physical shift backwards of the track after you stop recording, so not relevant.

Yes, try a longer “Audio to buffer” if it happens again.

If for example there was a Windows update for your built-in computer playback device and it was not a good update, playback could be stressing the computer more and this could be enough to disrupt the USB stream.

If you were using a USB hub before you were lucky not to have had the problem. Please do use an empty USB port.

These are some tips you could look at: .


Thanks for your help.