Microphone input Distortion through USB since 10.12.2

[UtterDisbelief]

As per the title I've discovered that I now have some serious ghosting distortion recording via USB microphone. I am unable to upload a sample file directly here as the site doesn't allow this so I've put it on Box.net here -

https://app.box.com/s/r3srlr2hoq9mczb7lkttuqd9nzd6jgq0

(Only 36k .m4a file)

Audio in and out works after the upgrade, so it's not a case of devices not showing or attached. System reports everything is fine. Output is as before - no problems.

I've tried two different USB microphones and my USB Webcam but the results are the same.

I can run reports if that helps (which ones would help specifically?) but wondered if this is a USB driver problem rather than audio?

Any ideas for a resolution appreciated.

Thanks

Edit: I've tried reverting the AppleHDA.kext to earlier Sierra versions, 276.26 and 278.23 (latest is 278.58) but this hasn't helped. It must be something else in the audio pipeline causing the problem.

 

[UtterDisbelief]

OK, sorted.

I've spent most of the evening trying to figure out what was going on and edited and reinstalled kexts like it's going out of fashion.

The result is I've now discovered what was causing this problem - a kext.

The microphone I have is a very nice, good quality Samson model and it comes with some noise-cancelling software in the form of a System Preferences pane. But it was difficult to spot what was being put where when the tiny installer ran. Sierra put the kext in L/E instead of S/L/E (which is what the .plist states) and - my bad - I missed it. This is what was causing the ghosting. Clearly it hasn't been updated for Sierra. Lesson learned.

Thanks if you went over this and tried to figure it out for me. I'm back to normal again. Noise cancelling? Pah!