pitch notation
...that the pitch notation developed by Hermann von Helmholtz for his work on acoustics and is one of two main systems for describing musical pitch?
...that the <b id="mwED4"><a href="./Helmholtz_pitch_notation" id="mwED8" rel="mw:WikiLink" title="Helmholtz pitch notation">pitch notation</a></b> developed by <a href="./Hermann_von_Helmholtz" id="mwEEA" rel="mw:WikiLink" title="Hermann von Helmholtz">Hermann von Helmholtz</a> for his work on <a href="./Acoustics" id="mwEEE" rel="mw:WikiLink" title="Acoustics">acoustics</a> and is one of two main systems for describing <a href="./Music" id="mwEEI" rel="mw:WikiLink" title="Music">musical</a> pitch?