Tone deaf test: method

What it measures

Pitch-direction discrimination threshold (the step heard correctly about 70.7% of the time), accuracy of reproducing short rhythms, and (optional) naming notes without a reference (absolute pitch).

Procedure

A sound check plays 4 rising notes to set a comfortable volume. All sounds are made in the browser (Web Audio): complex tones with harmonics 1 to 4 at amplitudes 1, 0.5, 0.3 and 0.15. Part 1, pitch: two 350 ms tones (25 ms fades) with a 400 ms gap. The first tone's frequency is drawn log-uniformly between 330 and 660 Hz on every trial; the second is higher or lower (50/50) by the current step. The player answers Higher or Lower (buttons, or the arrow keys); right or wrong is shown after each answer. Optional practice trials at 300 and 200 cents. The staircase starts at 100 cents; 2 correct answers in a row make the step smaller, 1 error makes it bigger; the step changes by a factor of 2 until the first reversal, then by the square root of 2; limits 0.5 to 400 cents; it stops after 10 reversals or 60 trials. Part 2, rhythm: 5 click patterns, each played twice with 4 units of silence between plays, then tapped back (button, Space or Enter); input closes 2.5 s after the last expected tap. Part 3, optional note naming: 12 single tones between C3 and B5 (never the same note name twice in a row), named on a one-octave on-screen keyboard; no reference tone and no feedback. Leaving the browser tab ends the run.

Parameters

Scoring

Pitch: threshold = geometric mean of the last 6 reversal points, in cents (also given as a percentage frequency difference); needs at least 2 reversals. Primary metric; lower is better. A semitone is 100 cents. Rhythm: the tap intervals are scaled so their total matches the pattern's length (tempo is factored out); error per pattern = mean over its intervals of |scaled tap interval − pattern interval| / pattern interval, each interval capped at 50%. A pattern counts as matched at 20% or less. A pattern with the wrong number of taps is not scored. Reported: patterns matched (of 5), mean error %, tempo ratio (above 1 = slower than played). Notes: an exact note name scores 1, one semitone off scores 0.75 (as in Athos et al. 2007); score % = credit / 12. No player comparison is shown.

Valid-run rules

The server replays the staircase from the right/wrong answers and rejects the run if the presented steps do not follow it, if a first tone is outside 330–660 Hz, or if the staircase had not finished (fewer than 10 reversals and fewer than 60 trials). Rhythm patterns must come in order and tap times must not go backwards. The note part must have exactly 12 rounds in range, or none. The server rebuilds every run from the raw log (and the run's seed where there is one) and computes the score itself; anything the page says about right or wrong is ignored. A log that breaks the game's rules is rejected, and nothing is stored. Stored runs can carry quality flags that are never shown and never block a result: 10 or more runs from one IP address, a missing visitor id, tab switches, and automation signals (automated browser, impossible speed, no input events, machine-regular timing).

Differences from the classic task

Lab pitch discrimination uses calibrated headphones, a fixed sound level and often several adaptive runs; here there is one run on the visitor's own speakers or headphones, with feedback after each trial. It is not the Montreal Battery of Evaluation of Amusia or any diagnostic battery. The rhythm part is a short reproduction task, not a standard beat test. The note part follows the scoring of Athos et al. (2007) but uses one synthetic sound and 12 notes.

Limitations

Speakers, headphones, volume and background noise change the threshold, and so does a single lapse of attention. Thresholds improve quickly with practice. Touch and keyboard latency affect rhythm taps. It is not a hearing test and cannot diagnose amusia. No norms for this version.

Languages and review status

Sounds are language-independent; note names and instructions in all site languages (English plus 99 other languages).