Setting up audio monitoring for a microphone on Ubuntu Linux
Channel: Daniel Rosehill
Date: 2021-08-10

If you're recording an audio device into Ubuntu Linux, then you might want to monitor the recording feed in order to make sure that everything is sounding good and all levels are properly configured.

It's not hard to set this up in Pulseaudio (at least for one mic; I haven't figured out how to pipe an individual output from multiple recorders yet). Just enter pactl load-module module-loopback from a terminal and you should see a loopback playback channel open for the default input device / microphone. 

You then just need to direct this to the right channel and you'll be able to monitor the audio. If you need to fix a latency or apply an offset, then you can also set this within Puleaudio itself by undocking the advanced audio properties options and configuring that manually.

On that note: this video is a good demo of how important latency offsets are. Yesterday, I accidentally deleted the 100ms offset that I configured in OBS Studio and you can really see the difference in how much more poorly the audio is in sync with the video feed. 

-- Production notes --

Microphone: Maono AU 902 (podcasting cardiod). Offset: 0ms.
Camera: Logitech C930e 1080P HD webcam
Software: OBS Studio
Lighting: Nil
OBS effects: Crop + some slight lighting and saturation adjustment in the filters. 

By: Daniel Rosehill (danielrosehill.co.il)