Stereo loop-back track produced during manual latecy test. How to force mono?

I’m using an external USB audio interface (UA Volt 476P) with a loop-back cable physically wired the output back into its mic jacks. It’s new, so I thought I needed to perform the Latency test (file:///C:/Program%20Files%20(x86)/audacity/help/manual/man/latency_test.html) before using it for overdubbing and multi-track recording.

The manual shows a screenshot of a MONO copy of the generated ping track being produced. However, I realized that Audacity actually produced a stereo track rather than a mono one during the ping.

My questions are:

  1. Does the fact that it is stereo affect the results of the latency test, and
  2. How do I force the looped-back copy of the ping to be mono, so that it is like what is shown in the manual rather than stereo? If it were mono, I could be sure that it is producing the correct results.


If you are running on Windows set both Windows and Audacity to mono.

…There is an “oddity” with Audacity when recording on mono from a stereo interface (or from a multichannel interface, which usually shows-up as multiple stereo interfaces).

When you record in mono the levels are cut in half so you don’t exceed 0dB or clip when both channels are combined. So if you are only using one input you can’t exceed -6dB.

If you record in stereo you can delete the silent channel after recording for true-mono.

Either way, you’ll have to “do something” after recording, but usually you’ll be leaving some headroom so you’ll need to make some post-production “adjustments” anyway.

Exactly. That is what is happening. The interface apparently only provides stereo channels, so Audacity always has to default to recording it in stereo. Something I didn’t expect during the latency test.