Interval Class Training

Two notes sit on one staff and you name the interval class between them — a number from 0 to 6. Count the semitones, reduce them mod 12, then fold anything above 6 back down, so a major third and a minor sixth are both 4. You answer on a seven-button pad or with the number keys, and every answer comes back with a one-line explanation of the arithmetic.

Four levels: naturals within an octave, which already contains every interval class there is; then sharps and flats join in; then any register, where compound intervals have to be reduced before you answer; then deliberately awkward enharmonic spellings mixed across treble, bass, alto and tenor clef, where the letters lie and only the real distance counts.

This one is eye-only by design — there is no ear-training mode and there isn't going to be. Interval class is a way of reading pitch relationships on a page when major and minor have stopped meaning anything, and hearing it named is a different skill from seeing it.

It's free and needs no account. Answers are logged to your progress in batches of ten if you're signed in.