Length - lowTreshold - highTreshold;

			analyser.getByteFrequencyData(dataArray);

			var barWidth = (scopeWidth - visualBufferLength) / visualBufferLength;
			var barHeight;
			var wx = 0;

			// only display range

			for(var i = lowTreshold; i < max; i++) {
				barHeight = dataArray[i] * (scopeHeight + (i * 2.5)) / 750;
				scope.fillRect(wx,scopeHeight-barHeight,barWidth,barHeight);

				wx += barWidth + 1;
			}
		}

		function clearScope(){
			scope.clearRect(0,0,scopeWidth,scopeHeight);
			scope.fill