Development of novel signal processing techniques for audio reproduction using loudspeaker arrays

Array technologies are a "hot" research topic in the field of audio capturing and reproduction. The latest research projects undertaken by the major national and international players in the audio and telecommunication industry (BBC, NHK, France Telecom, Deutsche Telekom, etc.) demonstrate the growing commercial interest in this field. The use of compact transducer arrays for the generation of private listening areas, to be used in conjunction with portable devices is a promising application of this technology.
The ISVR has a strong track-record in the development of DSP technologies for 3D audio reproduction with loudspeaker arrays. This is sometimes referred to as "Transaural audio". Whilst significant advances have been achieved recently in this field and the first Transaural audio systems have started to be commercialised, a number of issues are still unresolved and require more fundamental research to be carried out at an academic level.
Some of these issues are:
- Definition of optimal number of loudspeaker
- Reproduction of elevated virtual sources
- Reproduction of diffuse fields
- Importance of individualised Head Related Transfer Function
- Low frequency system instability and optimal size of the array
- Spatial aliasing at high frequency and determination of optimal loudspeaker spacing
- Reproduction for multiple listeners (2 or more)
- System adaptation to environmental conditions (reverberation and background noise)
The aim of this PhD project is to analyse these different problems and gain a better understanding of their scientific and industrial relevance. It is then expected that the project will focus on one or two of these aspects and develop novel solutions in terms of array design and signal processing strategies. It is expected that these novel solution will leverage ISVR's in-house expertise in array technology and may also be based on novel DSP approaches (e.g. compressive sensing) and on psychoacoustical principles (in which ISVR has also strong in-house expertise). The research work will involve both theoretical investigation and experimental activity, leveraginbg also the experimental devices and methods developed in course of the S3A project.
The improvement of 3D audio reproduction with loudspeaker arrays is a central topic of the S3A EPSRC-supported programme grant, to which this PhD project is associated. The outcomes of this project have significant potential for impact also through the S3A activity, which involves both academic and industrial dissemination of knowledge and technology.