Compact loudspeaker arrays for 3D sound reproduction

Lead Research Organisation: University of Southampton
Department Name: Faculty of Engineering & the Environment


Loudspeaker arrays are a hot-topic in audio signal processing. Their use for 3D audio and multi-zone audio reproduction has received much attention from both the academic community and industry. The Virtual Acoustics and Audio Engineering team at the ISVR has developed a significant expertise in this field, evidence of which is provided also by the research grants and industrial contracts that have been recently awarded to ISVR (current research budget in this field >£2M). Distributed arrays are widely used for surround-sound reproduction, but compact loudspeaker arrays have recently attracted much industrial interest, especially for their application as sound-bars or accessories for portable devices. ISVR has developed, in conjunction with the University of California, San Diego, a novel technology for near-field 3D audio reproduction using a small (20cm) loudspeaker array. This technology has been licensed to ComHear, a Californian start-up company, which is developing products that implement this technology. The latter is very effective for near-field reproduction (array-listener distance <1m) but it is not yet applicable for soundbars, where the listener is located at a larger distance. The improvement and far-field extension of this 3D audio technology is the objective of this project. This presents a number of interesting research challenges: firstly, the independent control of audio signals delivered to left and right ears of the listener, required for binaural audio delivery, is very hard to achieve when the listener is not close to the array. Furthermore, the listener may not be located directly in front of the array, so the listener must adapt to the listener position. The room reverberation, which does not play a major role for near-field arrays, should also be taken into consideration in this case as it may degrade the system performance. These are some of the challenges that will be faced during research project, the solution of which will require the development of new signal processing strategies and array design solutions. This project is of great interest for ComHear, which has expressed their intention to provide some financial support to this project.

Studentship Projects

Project Reference Relationship Related To Start End Student Name
EP/N509747/1 01/10/2016 30/09/2021
1786079 Studentship EP/N509747/1 26/09/2016 30/09/2019 Eric Hamdan
Description The work funded through the award for 'Compact loudspeaker arrays for 3D sound reproduction' has led to vastly improve theoretical and practical knowledge in the field of loudspeaker systems for reproducing personal 3D audio, particularly to do with so-called 'crosstalk cancellation' systems. These systems use two or more loudspeakers to reproduce binaural cues at the ears of a listener, giving them the impression of a 3D audio scene without the need for many distributed loudspeakers. During this work, the current theoretical understanding of crosstalk cancellation theory was expanded from the two-channel case to the multichannel case, thereby giving concrete and rigorous evidence previously unavailable as to why such systems benefit from more than two loudspeakers. This achievement was accomplished through detailed mathematical and experimental analysis conducted over the course of the award period. Novel physical evidence was obtained to support why multichannel systems are more robust than the common two-channel systems. In summary, the physical evidence suggests that at the core multichannel crosstalk cancellation systems are largely dictated by their ability to achieve so-called 'beamforming' and the extent to which a system can beamform effectively determines the system robustness and performance. As a consequence of this work, new theoretical knowledge was generated that is not only applicable to these systems but also to similarly formulated acoustic problems, in the mathematical sense, thus this award contributed not only to one field but has also contributed to new knowledge that can be used potentially by several fields, particularly those that deal with so-called 'inverse problems'.

As a result of these research outcomes, the application areas and questions for further work have only increased. This outcome has led to taking this largely acoustics and audio based technology to the medical sector, supported currently by a grant for introducing such crosstalk cancellation systems in the hearing aid and cochlear implant sectors within the UK and potentially abroad. These systems have the potential to improve spatial hearing tests and outcomes for a vast population of hearing aid and cochlear implant users. Furthermore, this work has led to several publications (currently in progress) that will hopefully be included in the most reputable acoustics and audio signal processing journals in the world.
Exploitation Route The most immediate and exciting application of the work funded by this award is to develop spatial hearing tests of the future for use in clinical audiology, specifically to improve spatial hearing outcomes of hearing aid and cochlear implants users. The technology developed from this award is capable of simulating 3D audio scenes that would otherwise be difficult to recreate in the clinical environment, with a small equipment footprint at lower cost than standard approaches used today. As such, it is envisioned, with the advent of bi-lateral hearing devices, that the work achieved has the potential to introduce entirely new benefits and spatial hearing tests that are simply not possible with the technology currently used in clinical environments today. Thus this work has contributed to the development of advanced 3D audio technology that has the potential to improve the quality of life for hard of hearing people within the UK and around the world.
Sectors Aerospace, Defence and Marine,Digital/Communication/Information Technologies (including Software),Education,Electronics,Healthcare,Leisure Activities, including Sports, Recreation and Tourism,Culture, Heritage, Museums and Collections,Retail,Transport,Other

Description The research conducted and findings as a result of this award have contributed to increased understanding of personal 3D audio systems and their practical implementation. As such, the fields which benefit from this technology have become better enabled and new potential applications have arisen. These fields include telecommunications, entertainment and most importantly the medical field, to name a few. This award contributed to a further research grant that is allowing the work to continue in the medical sector. While still in the early stages of investigation of this next stage, this work has shown promise to potentially impact the way spatial hearing tests are conducted and developed in clinical audiology. As a result of research and collaboration conducted under the award, it was found that the work has the potential to create new spatial hearing simulation and evaluation technology for use in clinical audiology. If successful, this technology has the potential to impact hearing aid and cochlear implant users globally by benefiting them with advanced spatial hearing tests, at a fairly low cost, that would allow for improved calibration and design of assisted hearing devices for future generations.
First Year Of Impact 2019
Sector Aerospace, Defence and Marine,Digital/Communication/Information Technologies (including Software),Education,Healthcare,Culture, Heritage, Museums and Collections,Other
Impact Types Cultural,Societal,Policy & public services

Description A compact and inexpensive virtual acoustics system for clinical and research evaluation of spatial hearing in cochlear implant and hearing aid users
Amount kr 660,000 (DKK)
Organisation Oticon Foundation 
Sector Charity/Non Profit
Country Denmark
Start 03/2020 
End 03/2021