How The Auditory Reaction Time Test Works
The test uses the Web Audio API to play a short 880 Hz oscillator tone after a random delay of 1.5 to 4 seconds from when you start a round. The moment the tone fires, the timer captures performance.now() on the audio thread. When you click (or press Space), it captures performance.now() again and subtracts — the result is your reaction time in milliseconds. This is different from the visual reaction test most sites offer: your brain processes sound through the auditory cortex (and brainstem for reflexive startle), not the visual cortex, and the two paths have measurably different latencies.
Why Auditory Reaction Is Usually Faster Than Visual
Textbook visual reaction time in healthy adults averages 200-250 ms, while auditory reaction averages 160-200 ms. The difference comes down to neuroanatomy: sound hits the cochlea and travels through only 2-3 synapses before reaching auditory cortex, whereas light must traverse the retina, optic nerve, LGN, and visual cortex before a decision can be made. If your auditory score on this test is significantly higher than your visual score (on a separate tool), the culprit is usually audio latency — wireless headphones or speakers with DSP processing add a systematic delay that has nothing to do with your nervous system.
What Affects Your Score
Caffeine, sleep, time of day, and age all shift reaction time by 10-30 ms each. Most adults are fastest in late morning to early afternoon and slowest late at night or immediately on waking. Fatigue and alcohol slow reactions dramatically. Practice helps for the first 5-10 trials as you learn the task, then plateaus. Hearing loss in the relevant frequency range (the 880 Hz tone sits in the middle of speech frequencies) can slow detection — if you struggle to hear the tone at moderate volume, that is a cue worth checking with a frequency response test.
Headphone And Speaker Latency
The test assumes sound hits your ears the moment the Web Audio timer marks the start. That is approximately true for wired headphones (under 10 ms), less true for USB-C DACs (10-30 ms), and very untrue for Bluetooth — SBC and AAC codecs add 150-250 ms between the browser and your ears. If you are running the test on AirPods or generic Bluetooth headphones, your measured reaction time is actually headphone latency plus reaction time, so the number will look much slower than reality. For a fair test, use wired output; for cross-session comparison, keep the same audio device.
