Simultaneous expressions

One or more music expressions enclosed in double angle brackets are taken to be simultaneous. If the first expression begins with a single note or if the whole simultaneous expression appears explicitly within a single voice, the whole expression is placed on a single staff; otherwise the elements of the simultaneous expression are placed on separate staves.

The following examples show simultaneous expressions on one staff:

\new Voice {  % explicit single voice
  << \relative { a'4 b g2 }
     \relative { d'4 g c,2 } >>
}

\relative {
  % single first note
  a' << \relative { a'4 b g }
       \relative { d'4 g c, } >>
}

This can be useful if the simultaneous sections have identical rhythms, but attempts to attach notes with different durations to the same stem will cause errors. Notes, articulations, and property changes in a single ‘Voice’ are collected and engraved in musical order:

\relative {
  <a' c>4-.  <>-. << c a >>  << { c-. <c a> } { a s-. } >>
}

Multiple stems or beams or different note durations or properties at the same musical time require the use of multiple voices.

The following example shows how simultaneous expressions can generate multiple staves implicitly:

% no single first note
<< \relative { a'4 b g2 }
   \relative { d'4 g2 c,4 } >>

Here different rhythms cause no problems because they are interpreted in different voices.

Known issues and warnings

If notes from two or more voices, with no shifts specified, have stems in the same direction, the message

warning: This voice needs a \voiceXx or \shiftXx setting

will appear during compilation. This message can be suppressed by:

\override NoteColumn.ignore-collision = ##t

However, this not only suppresses the warning but will prevent any collision resolution whatsoever and may have other unintended effects (also see Known Issues in Collision resolution).