%% http://lsr.di.unimi.it/LSR/Item?id=304

\relative c'' {
  \override TrillSpanner.bound-details.left.text = \markup{ 
    \musicglyph "scripts.trill" \raise #0.65 \teeny  \sharp }
  
  b1\startTrillSpan
  b1\stopTrillSpan
  
  \override TrillSpanner.bound-details.left.text = \markup{ 
    \musicglyph "scripts.trill" \raise #0.65 \teeny  \flat }
  
  c1\startTrillSpan
  c1\stopTrillSpan
}