The development and improvement of 3-D immersive audio is gaining momentum through the growing interest in virtual reality. Possible applications reach from recreating real world environments to immersive concerts and performances to exploiting big data acoustically. To improve the immersive experience several measures can be taken. The recording of the sound field, the spatialization and the development of the loudspeaker arrays are some of the greatest challenges. In this thesis, these challenges for improving immersive audio will be explored. First, there will be a short introduction about 3D audio and a review about the state of the art technology and research. Next, the thesis will provide an introduction to 3D loudspeaker arrays and describe the systems used during this research. Furthermore, the development of a new 16-element 3rd order sound field microphone will be described. Afterwards, different spatial audio algorithms such as higher order ambisonics, wave field synthesis and vector based amplitude panning will be described, analyzed and compared. For each spatialization algorithm, the quality of soundfield reproduction will be quantified using listener perception tests for clarity and sound source localization. / Master of Science

Detta examensarbete innefattar en utforskning om mitt arbete med immersivt ljud och hur det har påverkat min konstnärliga praktik som musikproducent. Utforskningen görs genom en analys av tre delstudier bestående av en 360-video som spelades in i S:t Jakobskyrkan i Stockholm, en VR upplevelse i en virtuell kopia av Nathan Milsteinsalen på Kungliga Musikhögskolan, samt en komposition som producerades med Dolby Atmos. Slutsatsen som dras är att arbetet har påverkat min konstnärliga praktik genom att ge mig nya insikter på komponerande, inspelning, och mixning. Slutligen ges förslag på fortsatta studier om audiovisuella metoder för immersiv musikproduktion samt nya infallsvinklar på stereomixning som är informerade av immersivt ljud. / This thesis examines how working with immersive audio has affected my artistic practice as a music producer. It does so by examining the insights gained during the production of three case studies consisting of a 360-video recorded at Saint James’s Church in Stockholm, Sweden, a Virtual Reality (VR) experience in a 3D replica of Nathan Milstein Hall at the Royal College of Music in Stockholm, as well as a composition produced using Dolby Atmos. The paper concludes that working with the case studies has changed my artistic practice by leading to new insights in the areas of composing, recording, and mixing. The paper also suggests future studies into the use of audiovisual approaches to immersive music production as well as considerations for stereo mix techniques based on insights gained from immersive audio.

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. / I den här examensuppsatsen utfördes en studie på hur man kan förbättra ljudupplevelsen i ett rum, när ljud spelas upp på en högtalare, genom att använda signalbehanlindning. Detta är ett ämne som blivit mer relevant, med mer och mer avancerade och prisvärda ljudsystem på marknaden. Målet för projektet var att hitta tekniker som gav en förbättring av ljudupplevelsen som både var robust och täckte en större yta av rummet. Lösningen var att designa ett korrektionssystem som uppfyllde kraven och tog vara på de stora beräkningsresurserna som dagens datorer erbjuder. Problemet och dess lösning förklaras tillsammans med en introduktion av varje ämne som påverkar ljuduppspelningen samt vad man kan göra för att motverka de oönskade sidoeffekterna. Det inkluderar områden såsom högtalarsystemkonstruktion, rumsaksustik, signalbearbetning och filterdesign, samt exempel och en diskussion på vidare utvecklingar av projektet. Projektet baserades till stor del på boken Immersive Audio Signal Processing av S. Bharitkar and C. Kyriakakis [1] som beskriver hur man skapar en inneslutande ljudupplevelse via rumskorrigering. Slutresultaten visade att det går att med några få steg bygga ett högtalar- och rumskorrigeringssystem som uppfyller de satta villkoren med mycket god ljudkvalitet. Även de enklare systemen, som bara använder en enstaka mätpunkt, kan korrigera för uppspelningen i ett helt rum med goda resultat. Genom att gå vidare med att undersöka att kombinera flera mätpunkter visades det att bara två välplacerade punkter kan prestera likvärdigt med att mäta över hela lyssningsytan. Däremot visas det att en kombination av mätningar över lyssningytan alltid presterar bäst.