"This sound zone concept is not new," explains Lee. "The concept has been proposed almost two decades ago. However, there are still technical challenges. One of the biggest is leakage from another zone.”
He elaborates, "It is often clearly audible while you are enjoying your own audio content. We have found some mathematical approaches to solving this problem. In other words, we now are able to make the bubbles more clearly separated.”
It uses “constructive and destructive interference”, continues Lee. "We aim to control multiple listening areas for different audio content in the same space without using headphones."
Lee explains that there are two steps that need to be taken in order to create multiple ‘listening areas’ i.e. specific spots that produce different audio.
“We create two types of zones, one where the sound pressure level is very high – namely the listening area – and a quite zone, where the pressure is as small as possible. Once these are defined, the audio content will be played back from loudspeakers to the listening zone while it is suppressed in the quiet zone,” he says.
“The sound pressure level on those zones are controlled by filters. We design those filters for each loudspeaker so that the zones are created as intended. Then we can obtain multiple listening areas for different audio contents when they are added (or overlapped) together.”
Lee admits for now his work remains in the research stage since there are still many practical challenges but adds that there is great commercial potential. As a result, the team is in the process of patenting the technique.
Examples of a potential applications include:
- Cars so that children in the rear seats can watch movies while parents listen to the radio in the front seat
- In the home where several residents can listen to music in the same room without disturbing each other
- At concerts and festivals where it can prevent sound on different stages from blending or disturbing neighbours
For this work, Lee has received the North Jutland University Foundation’s Innovation Prize. He and his research colleagues at the Audio Analysis Lab in the Department of Architecture, Design, and Media Technology hope that the extra attention the Innovation Prize provides helps them to develop the potential of the technology so that it can be used in the sound industry.
The prize amounts to around £5,850 and is awarded every year by the foundation board as an acknowledgement of and support for one PhD student. The student is recognised for having major innovation potential in their research area and is expected to contribute significantly to strengthening Denmark as a knowledge society. Particular emphasis is given to innovation, business potential, and solutions for specific societal needs and problems.