Hairpins in <a href="https://en.wikipedia.org/wiki/musical_notation" class="extiw" title="en:musical notation">musical notation</a>. Image made with <a href="https://en.wikipedia.org/wiki/GNU_LilyPond" class="extiw" title="en:GNU LilyPond">GNU LilyPond</a> and released into the public domain.
<p>LilyPond source:
</p>
<pre>\version "2.2.0"

staffline = {  
  \new Staff {
    \time 4/4
    \clef treble
    \notes {
      \relative c''{
        a4.\mf\&lt; gis16 a c4.\!\&gt; b8
        a4\!
      }
    }
  }
}

\score {
  \staffline

  \paper {
    indent = 0.0\mm
    raggedright = ##t
  }
}
</pre>
<a href="https://en.wikipedia.org/wiki/User:Camembert" class="extiw" title="en:User:Camembert">Camembert</a> at <a class="external text" href="https://en.wikipedia.org">en.wikipedia</a>
Transferred from <a class="external text" href="https://en.wikipedia.org">en.wikipedia</a>