The sound projector revolutionising audio

Researchers at the University of Sussex, UK, have developed a sound projector that tracks and delivers audio to moving individuals, with the potential to change the way audio is consumed in the future. Reece Webb reports.

Gianluca Memoli, senior lecturer in novel interfaces and interactions (Informatics), University of Sussex, is spearheading a project that aims to track moving individuals and deliver audio directly to them and no one else.

Memoli said: “I’ve been working with sound and different frequencies since 2005 and I’ve been working with fundamental sounds and a focus on the sound that bubbles make.I started working on metamaterials, which formed the basis of what we started doing in 2016.I wondered if there was a way to manipulate sound like we do with light, so I looked online and I found objects which were very chunky and quite disappointing.” 

Memoli and his research team set out to create a ‘sound projector’, capable of focusing and delivering sound to specific areas or individuals in an audience or space, using metamaterials to make objects smaller and manipulate sound. 

The projector currently creates a ‘ball’ of sound as big as a tennis ball, which follows the target that the projector is aimed at. Memoli explained: “If you think about a pilot who uses a pair of binoculars or a telescope to see a target, the rangefinder is rotated, adjusting the distance between two lenses until something is in focus.

“We do the same, but the other way around. We have two lenses, detect moving targets and we adjust the distance between the lenses and the angle at which the device points and eventually, we deliver a focal spot of sound to a person. It works like a camera with an autozoom function.” 

The technology could be used to develop ‘headphone-less’ listening experiences, providing a new way to consume audio in a way that is not isolationist, which is currently impossible with conventional headphones. Memoli said: “With headphones, we pump the volume enough to exclude the outside world. I am trying to create a technology which allows us to enjoy personal sound while staying in the outside world. I believe that when you want your own personal audio, you must use headphones, there is currently no other way. This might be a solution which makes our lives headphone-less.

“If you are at home, you’re walking around, and you want to have music delivered just to you, you can use headphones, but you lose interaction with the world around you and if we can get even faster with delivering audio then maybe we can send two different sounds to different people.”

The technology has a variety of applications in the commercial space, ranging from VR training environments to theatrical experiences in the form of “audio special effects”. Memoli explained: “If you want to interact with someone else, and enjoy the same content, you have to do that in the VR environment through headphones. The headphones provide a ‘fake’ sound that only deliver the impression of a sound when you could deliver sound directly to a user which moves with them, simultaneously allowing them to interact with other users. 

“In a theatre environment, we make all possible efforts to make sure that everyone has the same experience. Imagine that you can send sound to just one or two persons in the audience or to a group of people, or a shriek which surprises audience members, I think it’s a different way of creating spatial sound effects in a way that is significantly different to what we can currently do.”

The sound projector development could play a driving role in the push towards viable 3D communication technology, which relies heavily on immersive technologies. Despite audio playing a crucial role in this development, the industry has largely focused on immersive video and display technologies, with the audio aspect mainly being overlooked. Memoli clarified: “I think this is because the industry didn’t have the tools. We live in a world which is mainly visual, but even when you tell a story, without the audio it doesn’t really make sense.

“There has been a growing understanding that sounds have become a crucial part of our experiences. Sound is all around us, but you need chunky and expensive speakers to give an immersive experience. If you want to cover large audiences or deliver sound to specific persons, then you need a lot of speakers. That blocks development and the imagination in my opinion, so if we can develop systems that are user friendly and don’t require a lot of connected electronics, then I think people will start thinking about the audio side.”

"We are living in exciting times for audio because audiences are asking for more and this push gives us new ways to deliver audio,
we are living in a revolution." - Gianluca Memoli, University of Sussex
The breakthrough has not been without its challenges as Memoli clarifies: “There are two major challenges, the first being how many frequencies can pass through. The best we can currently do is two octaves, meaning they can be together or separated and you can have some notes on the other side but no more than 14 keys on a piano. As humans, we hear much more than that and that is the limitation that we are all trying to overcome.

“The other challenge is the size, which is something we have been working on throughout the year. When we started, our design was smaller than others you could find on the internet like the acoustic lens produced at the Bell Laboratories, which had a lens as big as a person. We’ve now managed to achieve the same effect with objects that are as big as a hand and we are getting smaller.” 

The development could also be used to help hard of hearing individuals, as Memoli clarified: “I could imagine that you could try to position the ‘tennis ball’ closer to the ear. Now, we produce standard delivery just below the chin because we found that people have different face lengths and facial features, so our current positioning allows us to accommodate more people in that way.

“If you knew that someone was hard of hearing, you could deliver audio very close or you could shape the sound, instead of just adding the lenses, you could shape the sound into a set of headphones.”

Memoli and his team are continuing to develop the technology, displaying the sound projector at the Siggraph Conference in Los Angeles, USA, with the team planning to exhibit new developments at the New Scientist Live event in London. Memoli: “There has been significant progress since July, getting feedback, ideas and requests. We are on the verge of operating at two Octaves and we plan to work with local artists to develop some melodies and test them with volunteers, finding out more about what they feel, but we’re still working on that.

“We had people who asked us ‘Did you try it on volunteers? What do they feel?’ We are trying to put a number and a statement on that question.”

Memoli closed: “It is being well received, people can see what is coming, but like every idea, we need to provide more numbers to substantiate our development in the scientific community. Others, who were not scientists, were extremely excited.“I try to create tools for creatives, that is what inspires me. I want something cheap and easy to do yourself, to send sound or create a 3D immersive experiences based on sound.” 

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