utton.innerHTML = "Play";
			}
		}

		function stopPlay(){
			BassoonTracker.stop();
			playButton.innerHTML = "Play";
		}

		// render a frequency scope
		function renderScope(){
			scope.clearRect(0,0,scopeWidth,scopeHeight);
			scope.fillStyle = '#000000';

			analyser.fftSize = 128;
			var bufferLength = analyser.frequencyBinCount;
			var dataArray = new Uint8Array(bufferLength);

			var lowTreshold = 8;
			var highTreshold = 8;
			var max = bufferLength-highTreshold;

			var visualBufferLength = buffer