(
  SynthDef(\help_playbuf, { | out=0, bufnum = 0, rate = 1, startPos = 0, amp = 0.1, sustain = 1, pan = 0, loop = 1|
      var audio;
      rate = rate * BufRateScale.kr(bufnum);
      startPos = startPos * BufFrames.kr(bufnum);

      audio = BufRd.ar(1, bufnum, Phasor.ar(0, rate, startPos, BufFrames.ir(bufnum)), 1, 1);
      audio = EnvGen.ar(Env.sine, 1, timeScale: sustain, doneAction: Done.freeSelf) * audio;
      audio = Pan2.ar(audio, pan, amp);
      OffsetOut.ar(out, audio);
  }).add;

  a = Pproto({
      ~newgroup = (type: \group).yield;
      ~sf1 = (type: \allocRead, path: "/path/to/sample.wav").yield;
  },
      Pbind(*[
          instrument:    \help_playbuf,
          dur:        Pseg([0,0,0.25,0.5, 0.75, 1],10).linexp(0,1,0.01,2),
          legato:        4,
          startPos:    Pn(Pseg([0,1], 20), inf),
          rate:        Pwhite(1, 1).midiratio,
          loop:        0,
          group:        Pkey(\newgroup),
          bufnum:        Pkey(\sf1)
      ])
  );
  a.play;
  )