How does the pitch discrimination test work?
Two tones play, one after the other, and one is slightly higher. Say which. The first pair is 100 cents apart, a semitone, the step between two neighbouring piano keys. After two right answers in a row the difference gets smaller; after a wrong one it gets bigger. Soon it settles at the edge of what you can hear.
Every pair starts from a new random tone between 400 and 800 Hz, so you can't compare it with one you remember. The test stops after the difference has turned round 8 times, or after 50 pairs.
How is your Pitch Discrimination Test result calculated?
Your result is your threshold in cents (hundredths of a semitone): the average of the last 6 points where the difference turned round, taken as a geometric mean. The "two right to go down, one wrong to go up" rule comes from Harry Levitt's 1971 paper in the Journal of the Acoustical Society of America, and settles where you answer right about 71% of the time. The site's tests run it against simulated listeners to check it finds their threshold.
Do musicians hear pitch differences better?
Usually, yes, and by a lot. In a 2006 study in Hearing Research, Christophe Micheyl and colleagues tested 30 classical musicians and 30 non-musicians: the non-musicians' thresholds started more than six times larger. Training closes much of the gap, though: new non-musicians needed four to eight hours of practice to reach the musicians' level.
Is this a hearing test?
No. It measures how finely you tell two pitches apart through whatever speakers or headphones you're using, at whatever volume they're set. It can't tell you anything about your hearing health; if you're worried about your hearing, see a hearing professional.
To name notes rather than compare them, try the Perfect Pitch Test; for the visual version of this test, the Color Difference Test.
What can affect your Pitch Discrimination Test result?
Your sound setup and your attention. Small phone and laptop speakers can blur the tones; the base tones here are 400 to 800 Hz, which most speakers play well, but headphones are steadier. Background noise makes small differences harder to hear. And one lapse of attention near the end moves the difference back up: the staircase treats a guess on a hard pair like any other wrong answer, so take each pair as it comes and use "Play them again" when you need to.