Question: Why does my USB microphone volume level act crazy during video conferences on my Mac?

Answer: Due to the COVID-19 pandemic many of us are now working, learning, visiting and even attending doctor visits remotely. We’ve had to learn to use video conferencing programs such as Skype, Zoom, Microsoft Teams and others. In doing so, many of us have found the convenience and great sound quality of using a USB microphone to be an advantage.

However, when using a USB mic on Mac computers, quite often users will find the conference application doing strange things with the microphone volume, either setting the volume way too high or setting it low when the user is speaking loudly but then not bringing the volume back up during normal speaking levels. As you can imagine, this can be quite annoying. The problem is the way the USB Audio Codec in the operating system interacts with the Automatic Gain Control (AGC) built into the application. Not to worry, there are some fixes for this!

First and easiest, some video conferencing applications will allow you to turn AGC off. Simply find the audio settings in the application and turn AGC off. If the application does not allow this you can create an “Aggregate Device,” which will work with a single mic. After doing this, the Aggregate Device acts as a go-between for the USB Audio Codec and the application, allowing the AGC to work properly.

Below are instructions for setting up an Aggregate Device.

Select and open Finder.

Select and open Applications, and then select and open Utilities.

Select and open Audio MIDI Setup.

Now, to add an “Aggregate Device,” hit the + sign at the bottom of the left column.

Select "Create Aggregate Device” when the window opens.

A new Aggregate Device will appear in the left column (in this example as “Aggregate Device 3”). On the right side of the screen select the USB microphone input (and output if your microphone has a built-in headphone out).

Now the Aggregate Device should be available as an input in System Preferences/Sound as well as in your application.

This should now allow the application to work properly with the USB microphone. If you have further questions, feel free to contact the Audio Solutions Department for assistance.