High pitched background noise.

Hi all,

I record footage for YouTube and it’s been fine but for the past couple of months I get this high pitched background noise when I record. Noise Removal does a good job of removing it but I’d like to locate the source of the noise.

I use a USB Blue Yeti for recording. It’s on a boom stand, not a desk.

Also, if I plug in USB headphones, I can usually hear the noise in the background without recording.

I’ve attached a sample of the noise so you can better understand what I’m talking about. Please help!


Yes. That’s our old friend “Frying Mosquitoes.”


It happens when the USB data lines “leak” into the audio system, usually by way of the USB 5 volt power system.

I’m afraid that’s full stop. The only way we’ve determined to get rid of it once you have it is to take apart your microphone or other device and run it from well-behaved 5 volts that doesn’t come from the computer, say a small laboratory power supply.

We’ve been testing USB isolators and filters with an idea to the quick fix, but so far, it’s not quick or a fix.

It does not appear to happen with higher end audio equipment. They have the money to spend on power processing that gets rid of this whine. In the case of sound mixers, usually the availability of 48 volt phantom power is the clue that they have such processing.

Everybody else is in the land of Noise Reduction.


Finally a diagnosis! Thank you for the information.

So if I were to replace my microphone, would that fix it for the time being or is this hardware within my PC?


Finally a diagnosis!

Yes, that flummoxed us for a long time. The noise changes with everything. Put a hub in, take hub out, lengthen the USB cable, shorten the cable, decrease the humidity, try it on Thursday … etc. One thing all those changes never did was reduce the noise to zero. That happened when flynwill did the lab power supply experiment.

would that fix it for the time being or is this hardware within my PC?


People use Yetis all over the world with good success, so chances are a lot of it is coming from your computer. People are building machines cheaper and cheaper and would you have noticed a problem with your USB keyboard or USB mouse if you never plugged a microphone in?

I did the long overdue sound test with my Shure X2U MicPre and digitizer. I’m using my ES-58 microphone (fake SM58). Attached.

It has the hiss that I complain about constantly but no whine. This device does have 48v Phantom Power, so it conforms to that rule.

The other rule is cost. The combination is about $200 usd…


… the Yeti comes in about $120. But the X2U is not a gift from the angels. I would not buy another one. It has low volume and high hiss noise. I have to scream at the microphone to get it into an overload condition and regular, every-day voice tracks are always low and noisy.

Much better is my sound mixer, same microphone and a Behringer UCA-202 digitizer. That comes in at about $230 usd. I bought my Macs with stereo Line-In connections intentionally, so I don’t need the UCA202. Now I’m at $200.

The down side is convenience. My system is clean, clear and very well behaved, but I have to know how to connect and drive a sound mixer.

I don’t know of any good inexpensive solutions… yet.


Putting this notch-filter code in Nyquist Prompt will do a better job at removing the whine than noise-removal …

    (setf s (notch2 s 567 15))   ; apply 567 Hz notch
    (let* ((q 15)                 ; set the base Q for the filter
           (freq 1000)            ; set base frequency
           ;set the number of iterations
           (iter (truncate (/ *sound-srate* (* 2 freq)))))
      (dotimes (i iter s)         ; start the DO loop
      (setf s (notch2 s (* freq (1+ i)) (* q (1+ i))))))

notch code in nyquist prompt.png

Thanks for the suggestion trebor, I’ll give it a go.

Koz, with that in mind id assume that the issue with my PC comes from either the PSU or the motherboard right? My PC wasn’t exactly cheap to build but my PSU is the cheapest part. Or would you suggest I ignore this and buy an external mixer/interface?


I do it with the mixer (powered from the wall) analog microphones and the interface inside my Mac. Generally, we like the UCA202 if you need an interface. It’s quiet, bidirectional and it’s certified for overdubbing because of its on-board headphone monitoring.

That’s the system doing a broadcast radio production.


OK, sounds good. So there’ll be no issue using a USB interface despite my USB leaks?


The problem comes when you combine molecular tiny microphone signals in the same box with USB.

In the case of the mixer working into a UCA-202, the mixer is carefully boosting the microphone signal and is supplying much higher line level stereo sound, not microphone level. So the show at the USB step is 1000 times louder than it used to be. flynwill proved the whine is still there, but it’s so low only the scientists are going to find it.


You can buy respectable USB sound mixers and not use the UCA202. I would stick with plain stereo and not fall to the siren call of 4, 8, and 12 channels of digital audio. Those are harder to record than you would think. There are odd rules for going over two-channel stereo.

If you make sure your mixer has, in clear English, “48 volt Phantom Power,” then the mixer has internal processing to filter the trash out of the USB connection, even though the mixer has USB and microphones in the same box.

It’s something of a juggling act.