(define (step-alteration pitch)
(let* ((diff (ly:pitch-diff (ly:make-pitch 0 0 0) (car pitches)))
(normalized-pitch (ly:pitch-transpose pitch diff))
(alteration (ly:pitch-alteration normalized-pitch)))
(define (step-alteration pitch)
(let* ((diff (ly:pitch-diff (ly:make-pitch 0 0 0) (car pitches)))
(normalized-pitch (ly:pitch-transpose pitch diff))
(alteration (ly:pitch-alteration normalized-pitch)))