Sample rate checker

Audio context rate is the rate this browser's audio engine runs at for this page. It needs no permission to read, which is why it appears instantly. On most systems it follows your default output device's shared-mode format, not your microphone, so treat it as the answer to "what rate does web audio run at here" rather than "what rate is my mic".

Mic track rate is what the browser reports for the capture stream after you grant mic access. Chromium-based browsers fill it in; Firefox and Safari often do not, and when a browser stays silent this tool says "not exposed" instead of guessing. The device name works the same way: browsers hide input labels until permission is granted, which is a privacy rule, not a bug.

The catch: resampling. Windows shared mode converts every app's audio to whatever format the device is configured for, so the browser can happily report 48,000 Hz while the microphone itself is set to 44,100 Hz, or the reverse. Both numbers above are the view after that conversion. When two devices in one chain disagree, something has to resample in real time, and that is a classic source of clicks. If you are already hearing it, see how to fix crackling and popping audio; a sample rate mismatch between devices is one of the usual suspects.

44,100 Hz is the CD lineage. The number was chosen in the late 1970s so digital audio could be stored on video equipment, and it stuck through the entire CD era. 48,000 Hz grew up in professional video and is now the default for games, streaming, USB microphones, and fresh Windows installs. Most rate mismatch problems are exactly these two rates meeting in one signal chain.

Both cover your hearing. A converter captures frequencies up to half its sample rate, so 44.1 kHz reaches 22.05 kHz and 48 kHz reaches 24 kHz, both beyond adult hearing. For voice, neither rate sounds better than the other; a matched chain beats a higher number every time.

Why mismatches crackle. When one device runs at 44,100 and another at 48,000, something in the path resamples in real time. Add two hardware clocks that drift slightly apart and buffers slip, which you hear as periodic clicks and crackle. Sample rate also pairs with buffer size to set your latency: the same buffer holds fewer milliseconds at a higher rate. The math is short and worth knowing; see what audio buffer size is.

Next step. The rate tells you how your mic is clocked, not how it sounds. For honest numbers on level, noise floor, and tonal shape, run the free mic test next; it measures in the browser the same honest way.