Sound measures how close your frequency guess is to the target — using logarithmic pitch space that matches how humans actually hear.
The Process
Map to logarithmic frequency space. Tones live between 80 Hz and 1,200 Hz (Easy) or 60 Hz and 1,400 Hz (Hard). Human pitch perception is logarithmic — an octave up always sounds like the same step, regardless of the starting frequency. Both target and guess are expressed as a 0-1 position on this log scale.
Measure distance. The absolute difference between your position and the target on the log scale. A distance of 0 means a perfect match.
Score via dual Gaussian. Two Gaussian curves compete — a sharp, tall one that rewards near-perfect matches (10 points at the peak), and a gentler, wider one that ensures you still get partial credit (up to 3 points) for being in the right neighborhood. Your score is whichever curve gives you more.
The Curve
The sharp Gaussian drops off fast — you need to be within a few Hz to score above 7. The gentle curve keeps you from getting zero when you're close-ish. The crossover point is around a score of 3, where the gentle curve takes over.
Score (0-10) vs log-frequency distance. White dot = your current guess in the demo below.
Why Logarithmic?
1
Pitch perception is logarithmic. The distance from 110 Hz to 220 Hz sounds the same as 400 Hz to 800 Hz — both are one octave. Scoring in log space means equal-sounding differences get equal penalties.
2
Precision matters more at the top. The sharp Gaussian means the difference between a 9 and a 10 requires extraordinary accuracy. But you'll always get a couple of points for being in the right octave.
3
No hue-style adjustments needed. Unlike color — where hue, saturation, and brightness interact — pitch is one-dimensional. The dual Gaussian handles the full difficulty curve on its own.
Try It
Drag the slider to guess the target frequency. Toggle Easy/Hard to see how the range changes. The score updates live.