TapNoiseStereo audio can place sounds differently on the left and right. Mono combines the channels, which can be useful when you want the full audio content available through either side.
Choose for your listening setup
Inspect System Settings › Accessibility › Audio for the stereo-as-mono option on your macOS version. Try a short, familiar sample before and after changing it.
Use the setting that serves your listening needs. Stereo width is an aesthetic choice, not a requirement for enjoying keyboard feedback or understanding an agent completion cue.
What changes in TapNoise
TapNoise places key sounds across the stereo field according to key position. With mono playback, that left-to-right spatial difference is reduced or removed because the channels are combined.
The selected theme and event still matter. Mono does not make a musical theme into a different instrument or change which physical key was pressed.
Diagnose one-sided sound separately
If one side is unexpectedly quiet, inspect the output balance and test another audio source. A balance setting, cable or earbud issue is different from intentionally using mono.
Avoid toggling accessibility audio settings as a blanket troubleshooting reset; another user may rely on them. For the specific balance control, see left and right audio levels. For a speaker-routing mismatch, use the output guide.
Source: Apple’s accessibility audio settings, TapNoise keyboard sounds.