MAIS OUI !
\version "2.24.4"
melodieA=\relative { \clef C \bar ".|:" c'4. d8 ees[ e! f fis] \bar "|" g2 }
melodieB=\relative { \clef F r16 \bar ".|:" c16[ ees g] c2 bes8 ais \bar "|" g4~g16[ e d ] }
\layout {
\enablePolymeter
}
\score {
\new PianoStaff <<
\new Voice { \melodieA }
\new Voice { \melodieB }
>>
\layout { }
\midi { }
}