Researchers from Washington University School of Medicine in St. Louis have developed a new hearing aid technology that can help people hear even in noisy environments.
The new open fit hearing aids with directional microphones let ambient sounds into the ear canal, unlike more conventional hearing aids, which completely block off the canal, which creates an occlusion effect that makes wearers' own voices sound a little like they are talking from the bottom of a barrel.
Directional microphones have been available for many years on conventional hearing aids that help users distinguish conversation from background noise by partially cancelling out low frequency sounds coming from the sides and from behind.
Because open-fit aids let sound pass directly to the eardrum, some believe this will lessen their ability to decrease background sounds.
The researchers tested the new technology in a loud restaurant set up with sound of plates and silverware and the clamour of voices.
"One of the most common complaints I hear from people who wear hearing aids is that they have stopped going to restaurants because they can't communicate. So we are testing hearing aid technology that might better help people hear in noisy places," said Michael Valente, Ph.D., director of the Division of Adult Audiology in the Department of Otolaryngology at the School of Medicine.
"We have a sound room set up to be an exact duplication of being in a loud restaurant. It's real restaurant noise, and it allows us to realistically test hearing aids," he added.
Open-fit hearing aids have been available for about three years. They are designed for people who have normal hearing in the low frequency range but have lost hearing in the upper range, where most conversational sounds are.
This is a very common type of hearing loss that often comes with aging or prolonged noise exposure.
"We found that the open-fit hearing aids with directional microphones on average gave wearers a 20 percent improvement in speech intelligibility in the restaurant setting compared to not having a hearing aid or wearing an open-fit aid without a directional microphone," said Valente.
"We are the first to show that a directional microphone in open-fit can provide improved performance in noise."
Moreover, the aids without directional microphones performed worse in the noisy situation than no aid at all.
"That's not unusual. People often tell me that when they are in a noisy situation, they take out their hearing aids because they don't help and sometimes even make it harder to hear," he added.
The study is published in the June issue of the International Journal of Audiology.