Measuring Loudspeaker Distortion and Room Reverberation Time Using a Speakerphone

Abstract: This master thesis project was carried out during the spring semester of 2016 at the company Limes Audio. The company specializes in making software, electronics, industrial design and mechanics with the aim to improve audio quality in loudspeaking communication systems. The performance of audio conferencing systems may degrade if there are distortions, or if the acoustical properties of the room are unfavorable. To ensure that the system works optimally, any unwanted effects must first be identified. This thesis will cover the necessary theory of acoustical systems and measurements. The implementations of three different measurement sequences are presented. The measurements are evaluated on three different speakerphone units and three venues to assess the accuracy of the presented methods. The results indicate that it is possible to use a single measurement signal, the exponential sine sweep, to measure both room acoustical reverberation time and loudspeaker distortion for a speakerphone setup.