(left-pitch (ly:event-property (event-cause left-bound) 'pitch))
(right-pitch (ly:event-property (event-cause right-bound) 'pitch)))
- (if (< (ly:pitch-semitones right-pitch) (ly:pitch-semitones left-pitch))
+ (if (< (ly:pitch-tones right-pitch) (ly:pitch-tones left-pitch))
-0.75
0.75)))