Windows 10 and unstable pitch

I am wondering if anyone else has found this problem when recording a musical instrument with a Windows 10 PC/laptop? I have posted previously and had great attention and help from Steve, Trebor and kozikowski.

Today I updated to Audacity 2.2.1

I checked the recording devices by right clicking the sound/speaker icon and disabled enhancements. The Laptop restarted.

I recorded myself playing repeated open string E - so no finger on the fretboard to induce any vibrato and there was again an unmistakable “wobble” in the pitch. It was less pronounced than in my previous recordings but clear enough to render it a problem.

I am using a USB mic which I bought to replace an old webcam that had done excellent service on a Vista laptop with a on older version of Audacity a few years back. The USB mic has the latest driver (well, updated on 4/12/2017 and the update box is greyed out in the properties tab).

I made the recording just now - with no other program or app running.

I am curious to know if this is a problem only I am having or whether others have encountered it too - and have found a way round it.

I have today recorded three guitar pieces - each of which has a few audible pitch wobbles occuring (seemingly) at random.

I am pretty sure it is not Audacity causing it, nor the mic. My suspicion is the windows10 laptop (a Lenovo G50). When I recorded guitar duets about 3-4 years ago using a Dell laptop running Vista with an older version of Audacity and recorded on a webcam mic, the results were superb. Sound was clean, bright and with absolutely no pitch issues.

Is it possible there is a conflict caused by the laptop and windows10 - and is there a fix?

[EDIT] Maybe it’s not a missing-samples problem… Occasional/random missing samples would lower the overall-average sample rate which would raise the pitch (when it’s played back at a the correct-higher sample rate). Trebor’s spectrum analysis shows a drop in pitch when it glitches.

Still, it wouldn’t hurt to try some ideas from the Glitch Free book.

I’m back to thinking it’s buffer/multitasking problem. (The operating system is always multitasking even if you’re only running one application).

If the clock (built-into your USB mic) is stable, the only possibility (that I can think of) is that the digital stream is being interrupted and you are occasionally missing samples. Usually… those kind of glitches are more gross & obvious but if you are sampling at a correct & constant rate and every sample gets written to the file, the pitch in the digital file has to be correct.

I suppose it’s possible that the drivers are corrupting the data stream, but I assume your USB mic uses the same Microsoft-supplied drivers that everybody else is using.

There is a free online book about optimizing your computer for audio called [u]Glitch Free[/u].

There’s also a free test-program called [u]DPC Latency Checker[/u] but there is a warning about incorrect results with Win8 so there may be issues with Win10 also.

Thank you, DVDdoug.

I have downloaded the Glitch Free link and read through quite a bit, and enacted all the Chapter 4 suggestions. I notice the “glitches” it mentions are of the pausing, stuttering and “clicking” kind, and don’t seem to include the one I have which is the momentary pitch wobble (which as you say is always a drop down rather than up).

I have now just recorded about 20 seconds of me playing a repeated open E string - and on playback, there were 3 distinct pitch wobbles.

I will press on and do all the other things it suggests in the hope that one of them will be the cure.

Thanks again.


I have encountered it once before. Here: Unstable pitch when recording acoustic guitar - #6 by Flamenco

Yes steve - that was me!