On swing jazz, soloists usually play at a different swing ratio than drummers, and actually sync up with the off-beat of the drums. The on-beat will sometimes have a delay of as much as 100 ms.

A bugle is a wind instrument that can only play its key note and notes within its harmonic series, for example, C3 G3 C4 E4 G4. To play different notes, one must change how the lips are placed on the mouthpiece of the instrument, which causes air to vibrate at different speeds, but the options are physically limited to integer multipliers of the base frequency.

When notating multiple flat notes in a single measure (e.g. B-flat, or "a semitone lower than B"), the symbol only needs to be applied to the first note in that measure.

The most common tuning system in western music nowadays involves dividing an octave into 12 equally spaced "semitones", called "equal temperament". In this system, the octave interval (frequency ratio 2:1) is the only "perfect" one, and, for example, a "perfect fifth" (frequency ratio 3:2) doesn't exactly match a "fifth" (seven semitones). This is the solution people came up with, and we've been using it happily for a while now, but there are other equally valid ways to split the octave.