Applying the EBU R128 Loudness Standard in live-streaming sound sculptures

This paper describes the development of a loudness-based compressor for live audio streams. The need for this device arose while developing the public sound art project The Overheard, which involves mixing together several live audio streams through a web based mixing interface. In order to preserve a natural sounding dynamic image from the varying sound sources that can be played back under varying conditions, an adaptation of the EBU R128 loudness measurement recommendation, originally developed for levelling non-real-time broadcast material, has been applied. The paper describes the Pure Data implementation and the necessary compromises enforced by the live streaming condition. Lastly observations regarding design challenges, related application areas and future goals are presented.