Mix and Render problems

Audacity MIX Mistake.jpg
Almost 60% of the time I Mix and Render multiple tracks into one, a portion or sometimes the whole track will be distorted into a loud buzzing sound. The wave is even distorted, it becomes a thick condensed looking wave form. I thought it was happening beacuse some tracks were muted or soloed or the gain was too high, but it doesn’t seem to make any difference what I do. I’m posting a photo to clarify.

Terrific graphics, but we’re still going to need the machine, OS version and Audacity version.
I’m typing this on a three year old Mac Mini, OS-X 10.6.8 and I use Audacity 2.0.3.


Thanks, photoshop. Thought it would make things easier to it. Mac Mini early 2009 running Mountain Lion 10.8 Audacity version

I take it you are aware that mixing is additive (less so if the sounds are dissimilar)?

Can you find a couple of short tracks that display this problem when mixed and rendered, then File > Export Selection each track as WAV. The WAV’s should be no longer than 5 or 6 seconds for stereo or 11 or 12 seconds for mono.

Please see here for how to attach files https://forum.audacityteam.org/t/how-to-attach-files-to-forum-posts/24026/1 .


I’ll try to reproduce it, I always delete them…

ALL 4.jpg
So it’s actually kinda interesting, what happens is the original rendered mix plays back the loud feedback buzzy sound but when I saved it as a wav the mix only has a slight buzz. I had to record the play back directly for you to hear sense the exported wav doesn’t have the full buzzy sound and I’m trying to send you both files but I cant figure out how to make the file size smaller without shortening the full length. I hope this makes sense. I also noticed that the photo of the distortion has the original sound hidden in there. I also recorded the screen of the original playback but I’m unable to send it because none of the file types are being accepted, what video files are accepted?.. It’s gotta be a glitch.

OK , figured it out and made them smaller to send… first one is the exported version that only has a little crackly buzz sound, which is strange considering what the playback sounds like. Second is the recording of the sound.

I couldn’t post this one last night because it was too soon after my last post, here’s the actual sound it makes when it plays.

Sorry to keep posting but here’s the link to the video : https://www.dropbox.com/s/cqgm808a0dj2gjl/Render2.mov

The “video” comes down as a really tiny file that QuickTime Player can’t figure out. Get INFO says the file is 4KB. Koz

Here’s a flash version, it plays for me. https://www.dropbox.com/s/te58nbca1wyhqq9/Render2-desktop.flv

Thanks for the files and video, but I don’t see how we are supposed to fix something that cannot be reproduced.

If you come across two tracks that have no noise when played together, but produce the noise when rendered, please Edit > Undo, select the first track you rendered in that operation then File > Export Selection as WAV, then select the second track you rendered in that operation and File > Export Selection as WAV that track.

Then Tracks > Mix and Render, listen, Edit > Undo, Tracks > Mix and Render and so on a few times. Does each render produce the noise, or only some of the renders?

Also are the rates (Hz) of each track (above Mute / Solo) and the rate of the project (bottom left) the same?


No it doesn’t happen all the time and if it does happen’ and I need it to mix, I export it and when it mixes down to two channels and it comes out fine. I love Audacity, its a great application. I just thought I might be doing something wrong, it’s probably a glitch… Thanks for trying to figure it out.


Someone on OS X with a different e-mail address than your registered Forum address wrote to our feedback address to say (paraphrased) that on OS X 10.8.3 using Audacity 2.0.3, if you mixed stereo tracks where clips did not overlap, the mix would “distort” in those regions where some tracks had white space.

To correct the problem, the user added silence at the start and end of the tracks.

Was this you?

I doubt this is platform-specific, but on Windows I mixed two arrangements, one mono, one stereo, with track gains turned down so there would be no clipping distortion.

Mono tracks:
mix of clips.png
Stereo tracks (the lower track in the below image is an M4A file, so it means Audacity has to mix 16-bit and 32-bit tracks).
stereo mixed clips.png
I did not find any problem when some tracks or channels had white space. The audio source is imported files.

What are the sources of your tracks? Are they recordings?

Are any of the tracks behind zero (you see a ← symbol at the left edge of the track)?

Have you been running effects on the audio, if so which effects?

Whoever wrote to feedback@, we need actual files that create this problem when mixed (if relevant, we would replace exported silence with white space in order to test),

If you believe exporting sounds less bad than mixing, we would need an Audacity project instead (AUP file plus the _data folder, zipped, with imported files copied into the project at File > Check Dependencies… before saving, closing and zipping).



Ok, I apologize for my very late response to everything because my email notification were off for some reason, but sample rates are always the same and I do make sure of this and as far as gaps in the mix, I never have them because it almost always a short sample with a fade out of one track overlapping to fade into the other one. I’ve basically adapted by knowing it’s a hit or miss, however now, I don’t know what I’m doing or what’s happening , but this started happening without even mixing tracks down. I’ll have 1 track and copy and paste a segment into a new track or just “split new” and press play and the same loud ass static buzz happens, what’s interesting though is if I place the the selector at some other random point on the tracks it doesn’t do it and for some reason this is happening more and frequently. And I’m pretty ignorant when it comes to sample rates, buffer settings and basically rely on what some friends have suggested and what I read in forums, so I basically I wasn’t messing with any default settings except for the basic output/input, maximum dB range and still trying to understand everything. And still love audacity, just wish I knew this stuff and wish there was just a few settings that needed to be changed. Apparently I’m the only one experiencing this and it’s driving me crazy.

Ok, I just experimented and split all tracks to mono and it stopped doing this, so that did something.

To be frank, there is little point writing about this further because as already explained, without an Audacity project that demonstrates the issue repeatably on someone else’s computer, there is nothing that can be fixed.

To repeat, we would need you to use File > Check Dependencies then copy in imported files (if there are dependent WAV or AIFF files that the project relies on), then File > Save Project, quit Audacity then make a zip of the AUP project file and the _data folder with the same name.

Upload the zip to dropbox, adrive.com, minus.com or other service of your choosing then let us know the web address where we can download the zip.

The only other thing you could perhaps do without giving us a project to look at would be to click Help > Audio Device Info…, click in the text, COMMAND + A to select all the text, COMMAND + C to copy it, then click the Code button in the posting window. Then paste the copied audio device info.


This is a long shot, but I recall having a similar problem a year or so ago. I’d get buzzing immediately on playback of a simple stereo project. The solution was to trash the preferences.

With Audacity not running, go to ~/Library/Application Support/Audacity and trash the “audacity.cfg” file.

If you have ever had Audacity 1.2 installed on your machine, go to ~/Library/Preferences and trash the “audacity” file.

Restart Audacity and load one of the problem projects and give it a try.

Note that your device settings will be reset to default and you will lose your “open recent” list.

– Bill

You’re right I guess there’s nothing more without having other people experiencing the same thing, but I will say that what seemed to fix it was one of the earlier replies, the gaps, the stereo to mono and throwing away preferences didn’t help but so far filling in the gaps with silence has worked, and it hasn’t done it anymore so…that’s it. Posting this because this may be helpful to say if it does happen to someone else. And I’ll leave it alone now… Thanks

Then maybe your sound device cannot cope with suddenly starting an audio sound when other sounds are playing?

Why not post your audio device info as suggested so we have some information to go on about what playback device you are using?