LilyPond whistle tones

Create whistle tones in LilyPond with small values to NoteHead #'font-size.

<<
   {
      \override Stem #'direction = #down
      \override Stem #'transparent = ##t
      \override NoteHead #'font-size = #-3
      \override Accidental #'font-size = #-3
      \override Script #'font-size = #-4
      \override Script #'padding = #0.5
      \override Script #'extra-offset = #'(-0.1 . 0)
      s64
      fs'''64 \flageolet
      ...
      e''''64 \flageolet
      \revert Stem #'transparent
      \revert NoteHead #'font-size
      \revert Accidental #'font-size
      \revert Script #'font-size
      \revert Script #'padding
   }
   \\
   {
      \override Beam #'font-size = #-3
      \override NoteHead #'font-size = #-3
      \once \override Script #'direction = #up
      \once \override Script #'font-size = #-4
      \once \override Script #'padding = #0.5
      <
         d'''
         \tweak #'duration-log #1
         d'
      >64 [ \flageolet
      \override NoteHead #'transparent = ##t
      \override NoteHead #'no-ledgers = ##t
      c'64
      ...
      c'64 ]
      \revert NoteHead #'transparent
      \revert Beam #'font-size
   }
>>

Two separate voices allow the harmonics and reference voice to stem independently.