Intermittent flutter on playback

OSX 10.9.5 iMac 2011 Audacity 2.1.0 dmg installation.

Hi, I’ve just used Audacity for the first time and am experiencing some annoying intermittent flutter sounds when listening to a playback of a 95 second acoustic guitar piece I recorded on Audacity. This flutter does not occur in the same place but can happen anywhere and at any time during playback. Aside from the occasional flutter, there is also sometimes an occasional clicking sound which again can happen anywhere or at any time during playback and before any effects have been added. This would seem to suggest that the recording itself is ok, but that this a playback issue.

(I’m a complete newbie so please bear that in mind when offering any advice.)

Which sound standard did you use? I use mostly 44100, 16-bit, Stereo. Does it still do that on that same clip after you restart the machine? And just to cover it, you don’t have a million applications napping in the dock and you have plenty of drivespace (how much) and you’re not trying to live play over a network?


Hi Koz. Thanks for responding.
I used all the default settings i.e. 32 bit, 44100 project rate, stereo, over 400 gigs drive space available on my internal hard drive, 8 gigs ram, no other apps were open during playback and no live network.

I have reduced the bit setting to 16 instead of 32 and the problem appears to have been resolved. I have yet to try the 24 bit setting.
Can you advise on what projects I can or should use the 24 or 32 bit setting as I believe I would get a superior quality recording if a higher bit ratio is used?

Also what is the 44100 project rate setting and when would I need to change this setting?

Also, I was most perturbed that when I recorded my vocal track, that it was out of sync with my guitar track but after much fiddling I finally was able to move/adjust the vocal track to line up with the guitar track - but is this normal? Is there no way that individually recorded tracks can be automatically lined up with each other?

Currently, I do not have an audio interface/sound card and am using my imac’s internal microphone to record vocals - the quality was better than expected but I need advice on how to get rid of sibilance as Audacity does not have a de-esser effect. The free download Soundfish de-esser is apparently not compatible for intel based macs, so is there another way of manually de-essing sibilance within the Audacity range of effects or is there a free de-esser plug-in available?

Thanks - jozi

am using my imac’s internal microphone to record vocals - the quality was better than expected

I have shot temporary theatrical tracks with my Mac built-in microphone and regularly use my Mac Stereo Line-In for paid gigs. Yes, they do work very well.

However, Macs now have microphone processing and as a fuzzy generality, it’s designed for speaking voices and hates music.

Apple (upper left) > System Preferences > Sound > Input. I’m not on a machine with a microphone, but there may be more options in that panel than you’re used to.

Here it is. [_] Use Ambient Noise Reduction (de-select).

That might be handy if you’re trying to Skype from a train station, but not for performance art.

Working up the list. If you’re overdubbing, there is an Audacity setting for Recording Latency. In English, it automatically lines up the new tracks with the old ones, but you have to set it because the settings are different for each machine.

Now you’re going to hit something I don’t know. I wrote the original overdubbing tutorials, but I used external sound devices and not the built-in microphone. My goal was a universal class applicable to anybody with any computer.

I’m thinking about this as I go. I guess you could jam your headphones down to the microphone. My microphone is just to the left of the left-hand shift key.

It’s a version of this:

I have no idea where your microphone is in an iMac, but you probably need to find out. This microphone to headphone exercise sets the system to overlay each track on top of the old one without timing problems (in a healthy machine). If you play a click track and record it like that, the different between the two tracks is the latency setting. It’s stupid simple.

That’s the overdubbing tutorial.

24 or 32 bit setting as I believe I would get a superior quality recording if a higher bit ratio is used?

Not exactly. What you get is better robustness. 44100, 16-bit, Stereo is the standard for Audio CD and that will take you beyond audibility both ways with very good fidelity. The digital television version is 48000, 16-bit, stereo. Slightly better high-end. If your job is simple processing and out the door, then either of those work just fine. Given that a great deal of product is MP3, anything higher than that is a complete waste of time (and drivespace).

But there are a couple of technical tricks needed to make that work and it starts to fall apart if you need serious post-production filtering, effects and processing. That’s when you shoot in 96000, 24-bit, Stereo. That’s the one you take into the post production edit suite with padded chairs and extra strong Starbucks. Venti, please.

It is concerning that the higher rates fail on your machine. I need to go back and read that again.


Attached is the version 3 Nyquist De-Esser. I’ve never used it.
DeEsser.ny (55.6 KB)

I was writing when Koz was, so to add a little more.

32-bit is much preferable if you are running a lot of effects on the audio.

Koz did not mention another setting which you should look at - “Audio to buffer” in Audacity’s Recording Preferences. On many modern Macs running recent Audacity versions, the Audio to buffer needs to be set down to a much lower value than the default 100 ms in order to avoid clicky playback. You may find that setting the buffer lower will avoid the need to go down to 16-bit in Audacity.

Also if you get yourself a proper external audio interface some day, it will probably be 24-bit capable. In that case you would need at least 24-bit default sample format in Audacity to give you the dynamic range your device is capable of. It would also be most important that you open /Applications/Utilities/Audio MIDI Setup and on the Input tab, set the sample rate, bit depth and recording channels of the interface to the same as the Audacity settings.

Project rate is bottom left of Audacity. If you choose an extreme high rate like 192000 Hz this puts much more strain on the computer than 44100 Hz. It does not give a significantly better recording for all the extra data. On some playback equipment it can sound worse than 44100 Hz.

If you got a proper mic and interface it would be less of a problem.


Thank you Koz and Gale for your informative responses and for the link to the de-esser.
I spent a lot of time fiddling with its settings, but found it to be un-reliable because the end result was un-natural sounding. I achieved a much better result by using the hard limiter on plosives, usually applying it 3 or 4 times to an individual ‘s’ consonant- time consuming, but I achieved a natural sounding end result.

I’m not sure that I want to over-dub tracks - I think each instrument and voice should be on a dedicated track before rendering a final mix, but thanks for the advice anyway.
Without an interface, I guess I’m resigned to not being able to hear myself in the headphones (cans) when laying down a vocal track. So until I can afford one, I’ll just keep one can on one ear and cup my other ear with my hand. I think the iMac’s internal microphone is inside the Apple logo on the face of the machine. I was at least two feet away from the iMac and aside from harsh sounding consonants, I’m pretty impressed with the quality of the vocal track as previously stated.

One thing that’s really worrying me, is the apparent lack of control for tweaking an individual effect that is near the beginning or middle of the chain of a whole range or chain of efx that one has added and then being able to either redo or edit or tweak them at a later stage.
The undo/redo option is fine for immediate undoing of an effect that has just been added, but does Audacity keep an accessible record of all the efx that one has added to a track and their individual parameters and allow you go back to either tweak or delete an effect that was added earlier on in a long chain of effects?
In other words, the ‘undo’ option only works backwards sequentially and apparently one would have to undo all the effects that have been added in order to access the effect that was added earlier on in the chain.


Correct. Undo is sequential. If you have effects A, B, C and D, you must undo C and D in order to undo B. You can work around this to some extent by keeping duplicates of tracks.

The list of effects and other actions (retained only while the project is open) is at View > History… .


Thanks Gale and for the advice on the controls in apps utilities folder.
I hope the audacity developers consider upgrading the effects editing software to allow for instant access to an effect in the chain without having to undo all the later effects added in the chain to get to an earlier one. I will certainly make a duplicate of a track each time I add an effect as you advised.

Very impressed with this forum.

Kind regards


I think each instrument and voice should be on a dedicated track before rendering a final mix

So do we. That’s exactly what overdubbing does. Track one is your voice. Track two is the violin. Track three is the trumpet.


I’ve recorded your “vote” for this on Wiki Feature Requests: