Empty Lyric lines taking up vertical space

[Ian Hawthorn]

Apologies for the long description of the problem.


I am typesetting barbershop arrangements for my chorus.

This type of music is typeset on two staves of two voices each. Most of
the time all four voices sing the same words, and at those times I need
a single lyric line centered between the staves. However there are often
syncopated portions where each part may need its own lyric line. The
lyrics for each voice are typset above and below the stave with two
lyric lines between the staves.

I am using a template similar to the SATB template which I modified from
an arrangement on the web.

\score {
  \context ChoirStaff <<
    \context Lyrics = tenorlyrs { s1 }
    \context Staff = TopStaff <<
      \clef "G_8"
      \partcombine
      \context Voice = tenorvox { \voiceOne \tenrNotes }
      \context Voice = leadvox { \voiceTwo \leadNotes }
    >>
      \context Lyrics = leadlyrs { s1 }
      \context Lyrics = barilyrs { s1 }
    \context Staff = BottomStaff <<
      \clef bass
      \partcombine
      \context Voice = barivox { \voiceOne \bariNotes }
      \context Voice = bassvox { \voiceTwo \bassNotes }
    >>
    \context Lyrics = basslyrs { s1 }
         
    % Now match up the lyrics with each part's notes
    \context Lyrics = tenorlyrs \lyricsto tenorvox \tenrWords
    \context Lyrics = leadlyrs \lyricsto leadvox \leadWords
    \context Lyrics = barilyrs \lyricsto barivox \bariWords
    \context Lyrics = basslyrs \lyricsto bassvox \bassWords
     
  >>

to suppress unneeded lyrics I have been making very frequent use of _.

The trouble with this is that lilypond always makes allowance for the
vertical space of each lyric line even when there are no actual lyrics
in it. Hence for most of the arrangement where there is only one lyric
line present (the lead), the lyrics are crammed up against the bottom of
the top staff to make room for the empty baritone lyric line. Also each
system takes up more room than is needed on the page as the staves are
often further apart than they should be, and furthermore lilypond makes
allowance for often empty lyric lines above and below the staves.

Can anyone suggest a modification to the template (or my use of it) that
might get around this problem? Can `_' be redefined so that it has no
vertical size? Does the vertical space allocation to empty lyric lines
deserve to be called a bug? Thanks for your thought.


Best Wishes
Ian H