Our bio-inspired research is improving lives as we contribute to the next generation of hearing aids.
We have developed innovative speech enhancement methods that will help eradicate the problem of background noise for hearing aid users and improve the lives of those with hearing loss.
Our research puts us at the forefront of a revolution in hearing aid technology.
It’s a situation most of us are familiar with – in a busy bar or restaurant, with lots of background noise and unforgiving acoustics, we struggle to make out what the person across the table is saying. In this sort of environment, picking out speech from the general hubbub can be difficult for those with normal hearing. For those with hearing loss it is often impossible, and can lead to social withdrawal, isolation and a poorer quality of life.
Through cutting-edge research into bio-inspired speech enhancement software, this is a problem that Stefan Bleeck, Professor of Hearing Science and Technology, aims to eradicate. His findings are generating interest among technology development companies and cochlear implant manufacturers, informing a new generation of hearing devices.
- In the UK, more than 11 million people have some form of hearing loss – one in six of the population.
- About two million people in the UK use hearing aids, but it is estimated that a further four million could benefit from them.
- Globally, disabling hearing loss affects, 360 million people – over 5% of the world’s population.
A bio-inspired solution
One of just a few research groups in the world working on this type of technology, Stefan and his team have developed innovative signal processing software that can be ‘trained’ to distinguish between speech and background noise.
“It’s easy to make a hearing device that makes everything louder,” says Stefan. “But sometimes that doesn’t help because the speech you want to hear is quieter than the background noise. So the challenge is to develop a device that can identify and enhance the speech only.”
Drawing on Stefan’s expertise in brain physiology, the research uses artificial neural networks – computer programmes inspired by the brain’s auditory functions. “We repeatedly present the network with noisy speech, and tell it which part of the mixture is speech and which is unwanted sound,” says Stefan. “Over time, it learns to apply this knowledge and will start to recognise the speech parts, enabling it to select the right part of the mixture to enhance. We can then resynthesise the sound in hearing devices to improve the intelligibility of the speech. The fundamental difference compared to traditional techniques is that rather than trying to suppress the noise – an approach that has failed for more than 50 years – we try to enhance the speech, taking the same approach as the human brain.”
Improving clarity
A significant advantage of this method is the quality of sound it produces. Stefan says: “Other algorithms have been developed that can reduce noise, but the speech sound they produce is robotic, unpleasant to listen, and not necessarily any easier to understand. Our technology produces a clearer, more intelligible and more natural sound, leading to devices that people will be happy to use.”
The technology has been successfully tested with hearing impaired people and cochlear implant users, in studies funded by the Engineering and Physical Sciences Research Council and the European Commission’s Horizon 2020 programme. “We were the first to apply the technology in real time for people with cochlear implants,” says Stefan. “We worked on this study with Cochlear, a cochlear implant company, who were very impressed with the results.”
Driving a revolution in hearing technology
These developments are driving change at a pivotal time for hearing technologies. Stefan sees his work contributing to a future in which people no longer see a boundary between hearing devices and other consumer electronics, helping everyone to communicate better in noisy environments.
He says: “The US Food and Drug Administration, one of the most influential healthcare regulators in the world, recently changed its guidance, so that hearing aids no longer require a medical evaluation. This heralds a revolution in terms of their availability, because it will eventually remove the restrictions under which they are currently dispensed, including in the UK.”
The commercial implications of this decision are recognised by technology companies, dozens of which are now developing over-the-counter hearing devices known as ‘hearables’. Crucially, these could be used to amplify sound in a personalised manner, although they have not yet been developed to do so because current health legislation doesn’t permit it.
“The development of hearables will make a big difference to the way hearing aids are perceived and their availability in the near future. Hearables and hearing aids will merge, the devices will be cheaper and more powerful, and many more people worldwide will benefit from them,” says Stefan.
Understanding user needs
However, few companies are approaching technological development from a user perspective, and this is where audiologists can add real value. “We understand the point of view of the hearing impaired person,” says Stefan. “We need to bring users into the loop, so that they get something that they actually like, want and perceive as a benefit. If people aren’t satisfied, they won’t wear their devices – around a third of NHS-prescribed hearing aids end up at the back of a drawer.
Changing the policy landscape
These radical changes will have a big impact on the audiology profession, and Stefan is working to ensure policy reflects new practices. “I’m involved in ongoing discussions with the British Society of Audiology. At their next annual conference I’ll be setting out my roadmap for the future, one in which we can improve the help we offer to people with hearing problems with a new generation of hearing devices.”
Our work on speech enhancement will inform the development of devices that will really meet people’s needs. In turn, this will reduce some of the negative socioeconomic effects of hearing loss, such as isolation and depression, that are often overlooked.