Auditory Reaction Time Test

You react to a sound faster than to a light, usually by 30 to 40 milliseconds. The reason sits in your ear and your eye, not in your brain.

Your ear works like a microphone. Sound physically moves tiny hairs inside it, and that movement is the signal, so it sets off almost at once. Your eye works more like photographic film. Light has to set off a chain of chemical reactions inside the eye before any signal leaves it, and chemistry is slower than movement.

You can measure the gap on yourself. Take this test and the visual reaction time test back to back on the same equipment, then subtract one from the other. Most people find 20 to 50 ms. If you find nothing at all, your headphones are the likely cause rather than your ears. The next section explains why.

With a light we start the clock on the frame that draws it. A sound has no frame. Your browser hands the tone to your sound card, which keeps its own clock, running separately from the one that draws the screen.

So this test converts between the two clocks. It books the tone for an exact moment on the sound card's clock. It then works out when that moment falls on the main clock, and starts timing there.

What no browser can see is what happens after the sound card. Bluetooth headphones delay the sound by anywhere from 30 to over 200 milliseconds, and nothing in the browser can detect it or correct for it. Wired headphones and wired speakers add close to nothing. Take this test on Bluetooth and you are mostly measuring your headphones, which is why the tool warns you on the start screen.

It is a plain 1000 Hz tone, 60 milliseconds long. It fades in and out over 5 milliseconds at each end so it does not click.

That fade matters. A tone that starts instantly makes a faint click of its own, and some people react to the click slightly before the tone. That would make scores look better than they are.

You can change the pitch because hearing is not equally sharp at every pitch. Most people hear best between 2 and 4 kHz. People who have lost some high-pitch hearing often react much faster to 440 Hz than to 2000 Hz. That gap is real, but it is about how well you hear the tone, not how fast you react. This is not a hearing test. If one option is inaudible at a volume where the others are comfortable, mention it to a hearing specialist.

Every warning about browser reaction tests applies here, plus one more. Your score includes a delay from your audio equipment that we cannot measure. So compare your sound scores with your own earlier sound scores on the same equipment first, and with other people second.

The age curve comes from tests using light, so it applies here in shape only. What counts as a good reaction time sets out how much of any such number is really your hardware.

Two practical notes. Do not close your eyes. It turns the task into something closer to a flinch. And do not crank the volume to chase a faster score. Louder tones do shave off a few milliseconds, so a loud run cannot be compared with a quiet one.