Speaker Test

How to read each check

Left-only sound must come from the left speaker or earcup and right-only from the right — if they are swapped, swap the plugs or the balance setting. During the polarity check the in-phase burst sounds full and centred while the out-of-phase burst sounds thin and wide on correctly wired stereo; on a mono device the out-of-phase burst nearly cancels out, which also confirms correct wiring. During the sweep, note the frequencies where you hear buzzing, rattling or dropouts — those mark cabinet, mounting or driver issues, not microphone problems.

Set up a fair channel check

Sit centred between the speakers, set system volume near 30%, and run Left, then Right, then Center with no equalizer or surround mode engaged. Each press fires a short 440 Hz blip through the Web Audio API entirely on your device, with no microphone permission and nothing recorded, and it works in current Chrome, Edge, Firefox or Safari with no account or download. On headphones the center blip should land inside your head, on a desk pair it should image halfway between the boxes. Turn off spatial audio and bass boost first, because those effects smear a clean left-right answer.

What the polarity flip is telling you

The button plays two 440 Hz bursts back to back: the first drives both channels identically, the second inverts the right channel. Correctly wired stereo renders the first burst full and tightly centred and the second thin, diffuse and pushed to the sides, because your ears receive opposing pressure. A single mono kitchen speaker behaves differently and usefully — the second burst nearly vanishes as the two opposing signals cancel inside one driver, and that near-silence also confirms the path is wired consistently. If both bursts sound identical and centred, suspect a mono downmix in the operating system, a single-earbud Bluetooth mode, or an accessibility setting forcing mono audio.

How to run the 12-second sweep without hurting gear

Start the 20 Hz to 20 kHz logarithmic sweep at conversation level, keep your finger near Stop, and jot the pitch where anything changes character. Tiny desktop cubes and phone speakers cannot move much air near 30 or 50 Hz, so expect a quiet entry, a swelling mid-bass near 90 to 140 Hz, then a smooth climb into a piercing top octave past 10 kHz. Louder does not reveal more; pushing the sweep to maximum to force bass from a 2-inch driver only heats the coil. Play the same sweep once per side by panning balance left and right in system settings, and you will isolate whether that rattle at 180 Hz lives in the left cabinet or the right shelf.

• Note buzzes as ranges, for example 110 to 150 Hz on male voice or 2 to 4 kHz on sibilance, rather than single magic numbers.
• Touch the cabinet lightly during a buzz — a rattle that stops under fingertip pressure points to a loose screw or grille.

Turning a buzz diary into a fix

You bought a used pair and the left box rattles on bass guitar. Sweep again at modest level, confirm the disturbance clusters near 130 Hz, tighten driver screws a quarter turn and press the grille pegs home. Your new soundbar images right of centre. Replay Center, swap the left and right inputs or re-run room setup, then replay Center — when the image snaps to the middle you have proof, not a hunch. One Bluetooth earbud crackles only on the top octave. Clean the tip, test Left versus Right with the steady tone generator, and check the frequency spectrum view. For background level context, glance at the decibel comparison chart.

Keep it safe

Short bursts at moderate volume are enough. Deep bass at high level can damage small speakers, and long high-frequency tones tire ears fast. For hearing screening instead of hardware checks, use the hearing age test; for steady reference tones, use the tone generator.

Tone generator → · Hearing age test → · Microphone troubleshooting →