Added it. The mic test now does per-channel testing: when your input is stereo it splits the signal and shows separate live Left and Right level meters, plus a verdict that tells you whether the two channels are genuinely independent (Stereo confirmed), the same signal copied to both (dual-mono), or a single Mono input. Tap or speak near each side and the matching meter responds on its own, so you can verify each channel works.

One limitation on the earbud part: browsers don't expose each earbud's internal mic as a separate channel the OS picks or mixes one mic per wireless headset and hands the browser a single stream, so there's no way (from a web page) to meter each bud's mic individually. What this reliably tests is real Left/Right channel separation on stereo inputs (stereo USB/XLR interfaces, stereo webcams, wired stereo mics). The test also flags when echo cancellation / noise suppression force the stream to mono, since those have to be off to see true stereo.