Speaker Test (Left/Right, Phase, Sweep)

A test for new speakers, earbuds or headphones: are left and right the right way round, does one side stay silent, and is one speaker's +/− wiring reversed? The sound is generated in the browser, so there is nothing to download.

Left, Right and Both play pink noise (or a 440 Hz tone) on that channel only. Pink noise, a hiss with equal power in every octave that sounds more balanced to the ear than white noise (equal power per hertz), is the easiest sound to place by ear. Alternate swaps sides every second. The two level meters show the signal actually leaving the browser on each channel, so if a meter moves but you hear nothing, the problem is the output device or the cable rather than the page.

The phase test plays the same sound on both sides: in phase, both channels identical; out of phase, the right channel inverted. On correctly wired speakers the in-phase sound sits firmly in the centre with full bass, and the out-of-phase sound spreads out and loses its bass. If it is the other way round, one speaker's + and − leads are swapped. The correlation reading shows how alike the channels are: +1 in phase, −1 inverted, 0 when only one side plays.

The sweep is a sine wave rising from 20 Hz to 20 kHz over 15 seconds. Where it fades in and out gives a rough idea of a speaker's range, and a buzz at some frequency points to a rattle. Your ears and the room dominate, so it is not a measurement. Start with the volume low.