Loudspeaker-Room Correction of Conference Rooms

Sammanfattning: In this Thesis a study on the subject on how to improve the overall sound quality within a room using signal processing, played back using a loudspeaker, was conducted. This is a subject that has gained attention during the recent years, with more and more consumer and professional products including it. The objective was to find techniques that offered perceptually good audio quality covering most of the room, while being robust and stable. The solution was to design a correction system which fulfilled these requirements and took advantage of today’s computing technology. This problem and its solution, as included in this Thesis, expose the reader to an introduction to loudspeaker system design and reproduction, room acoustics, psychoacoustics (how humans perceive sound), signal extraction (pre-processing) and filter design as well as design considerations for all of these components. Different ways that this system can be developed further were also discussed. This thesis was mainly based on the theory explained in Immersive Audio Signal Processing av S. Bharitkar and C. Kyriakakis [1]. The results of experiments show that a well-performing room correction system can be realized using a microphone with a known response and a computer. In most cases the improvement in both audible and measurable audio quality is considerable, with only a few cases where an improvement was not made. Using multiple measurement positions, positions of the microphone, led to a further improvement. On the other hand, it was also shown that having two well-positioned microphones was shown to be close to as performant as covering the whole room, even if a combination measurements over the whole listening area was the best performing approach.