6.4.9 Writing music in parallel

Music for multiple parts can be interleaved

     
     \parallelMusic #'(voiceA voiceB) {
       r8     g'16[ c''] e''[ g' c'' e''] r8     g'16[ c''] e''[ g' c'' e''] |
       c'2                                c'2                                |
       r8     a'16[ d''] f''[ a' d'' f''] r8     a'16[ d''] f''[ a' d'' f''] |
       c'2                                c'2                                |
     }
     \new StaffGroup <<
       \new Staff \new Voice \voiceA
       \new Staff \new Voice \voiceB
     >>

This works quite well for piano music

     
     music = {
       \key c \major
       \time 4/4
       \parallelMusic #'(voiceA voiceB voiceC voiceD) {
         % Bar 1
         r8  g'16[ c''] e''[ g' c'' e''] r8  g'16[ c''] e''[ g' c''
     e''] |
         c'2                                 c'2 |
         r8  a16[ d'] f'[ a d' f']       r8  a16[ d'] f'[ a d' f'] |
         c2                                  c2 |
     
         % Bar 2
         a'8 b'      c'' d''    e'' f''    g'' a'' |
         d'4         d'         d'         d' |
         c16 d e f   d e f g    e f g a    f g a b |
         a,4         a,4        a,4        a,4 |
     
         % Bar 3 ...
       }
     }
     
     \score {
       \new PianoStaff <<
         \music
         \new Staff <<
           \voiceA \\
           \voiceB
         >>
         \new Staff {
           \clef bass
           <<
             \voiceC \\
             \voiceD
           >>
         }
       >>
     }

Other languages: French.