Whether you’re using your PC for conference calls, audio recording or online multiplayer video gaming with a headset, both USB and analog audio, you quite likely stumbled across that issue. Since your computer normally isn’t set up to output your own voice, other people participating in your calls are first to complain about background noise from your side. If that background noise sounds like a constant buzzing or humming, it’s a ground loop (Wikipedia: Ground Loop). An easy way to find out if you got a ground loop is to disconnect your laptop from the power outlet. The noise should be gone immediately and those people on the other end should be fine.
There are hardware solutions to that problem and I absolutely recommend sticking to those if you like to properly record from your microphone. Usually, they involve a certain setup, cables and more often than not, patience and luck. For instance, you can touch any grounded part like USB ports or metal surfaces of your laptop with your fingers and the noise is reduced as well. I like to talk without touching my devices all the time.
Sometimes, you can neither choose the quality of your local electric grid nor the grounding of your USB headset as well as your laptop, leaving only software solutions. Right now I’m changing my location once in a while and although I’m lucky in finding WiFi hotspots even in a jungle, I didn’t encounter a stable electric grid including properly grounded devices too often in South America. I’m using a run-of-the-mill Logitech USB headset and an Asus Zenbook.
Microphone recording with ground loop noise (use headphones to listen):
There is a simple solution that works with any device:
- Install a microphone equalizer
- Filter out ground loop noise
After applying the filter:
Detailed Instructions (USB Headset, Windows 10)
- Install EqualizerAPO (Sourceforge: EqualizerAPO)
- When installing and running the first time, EqualizerAPO will ask you to choose the device that you’d like to have an Equalizer installed to in the Configurator. Choose your headset microphone from the Capture devices tab and click OK:
- Download this ZIP archive and unzip the included filter file (.txt) to a location of your choice: filter-ground-loop-noise-60Hz.zip
- Start the Configuration Editor and configure EqualizerAPO to use the filter file using the existing Include section:
That’s it! You can use the default voice recording app or do a Skype test call to check if the noise is gone, or temporarily enable “Listen to this device” in your Windows recording devices system settings.
Please leave a comment if you have any questions, something didn’t work as expected or in case you got an easier solution.
If you are interested in how and why that filter works, read on. If not, enjoy your day and talk to people!
The filter set strongly dampens parts of the frequency spectrum in your microphone’s recordings, more specifically only those frequencies that constitute the ground loop noise, leaving other frequencies untouched. It works best with power grids that run at 60 Hz, like basically all grids on the American continent. Filtering out only 60 Hz itself isn’t sufficient because the ground loop noise includes a lot of harmonic frequencies (or overtones) above 60 Hz, more specifically multiples of 60 Hz. Actually, 60 Hz is not an issue since most audio/video calling systems filter out frequencies that low anyway. The most annoying parts of that noise are 180 Hz and a lot of overtones between 420 Hz and 720 Hz.
The spectrum before and after the filter illustrate how dirty that noise is:
The filter removes those frequencies: 60 Hz, 120 Hz, 180 Hz, …, 780 Hz, 840 Hz. Its frequency response looks like this:
I encountered some power grids whose frequency is fluctuating a lot (+- 5 Hz) around 60 Hz so that filter isn’t perfect. Since it also removes essential parts of your voice, I tried to keep the damage low and used a set of peak filters with a very high slope.
You can easily adapt that to other frequencies, like for instance 50 Hz in Europe: filter-ground-loop-noise-50Hz
Filters for some higher overtones are disabled (commented out) because my call partners weren’t that annoyed by those sounds. It should work sufficiently well for you but if it doesn’t, play a bit with that filter set.
Thanks for reading!