What was the design purpose for OpenSound Navigator?
The reason we created OpenSound Navigator was to allow individuals with hearing loss to be able to continue to engage as much as they want to in the types of social situations that they find positive. We don't feel that speech communication should solely be considered a one-to-one situation. There are plenty of opportunities for individuals with hearing impairment to have the opportunity to engage in conversations with more than one person at a time, in group situations. Even in conversations with one person at a time, it shouldn't feel like you're in a communication bubble where that's the only thing that you hear. Oftentimes, we are in situations and environments where the full sound experience is important. Simply put, the design purpose of OpenSound Navigator is to improve speech understanding performance in complex environments without unduly sacrificing a natural listening experience.
A variety of technologies have been developed over the years. Traditional directionality and noise reduction essentially plateaued about 10 years ago or so. The signal processing routines that were incorporated in traditional directionality and noise reduction didn't seem to be evolving much beyond the principles that were put in place 15 or 20 years ago. The principles of adaptive automatic directionality and also automatic noise reduction in hearing aids (modulation-based long-term noise reduction) entered the marketplace about 15 or 20 years ago. These principles were refined but then remained static for a number of years. As such, patients were still running into some amount of difficulty.
One reaction that came out of the hearing aid industry was the idea of creating beamforming. Beamforming, as you know, is a technology that became available once we were able to achieve wireless connectivity between the two hearing aids. With the four microphones available, we were able to create a much narrower listening channel for the patient. That was considered the next step in environmental sound processing for patients with hearing impairment. Beamforming was effective in that if you were listening to one person directly in front of you and they were not too far away from you (within a meter or two), beamforming can create this narrow channel to allow you to hear.
The problem with beamforming is that you were creating a "hearing isolation tank" for the listener, rather than focusing on a fully natural listening experience. Essentially, the beamforming mentality was that since sensorineural hearing loss is such a difficult problem to solve, the only way we can solve it is to dramatically restrict what the patient has to listen to, and that's the best we can do. However, over time, we felt that that wasn't the best we could do. We believed that we could improve patient's performance in complex environments without putting this unnatural restriction on being able to hear more of the sounds in the environment. That's why we created OpenSound Navigator.
With OpenSound Navigator, we are proud of the fact that, via high-quality research using independent sources, we've been able to close the gap between hearing impairment and normal hearing. In the complex environments under which we test, we've been able to demonstrate that individuals with sensorineural hearing loss using OpenSound Navigator can perform on par with normal hearing individuals in similar situations. We are not claiming that we are able to restore hearing to normal. There is still a disordered hearing system. However, under the complex listening conditions in which we have conducted testing, we have been able to show that hearing impaired individuals with OpenSound Navigator can perform at similar levels to people with normal hearing. We consider it to be a great sign of success that OpenSound Navigator allowed us to achieve those results.
This Ask the Expert is an excerpt from The Behavior of OpenSound Navigator in Complex Environments. Learn more on the Oticon Expo Page on AudiologyOnline.