Technological Advances in Hearing Aids

When programming hearing aids, audioprosthetists need to make sure they’re giving their patients enough amplification and the best sound quality possible. However, given every patient is unique, there is great variability between individuals, which can create some challenges when it comes to programming hearing aids.

In fact, a study of 30 participants showed that they experienced the vent effect very differently, even when they were wearing the same type of dome. The vent effect is the loss of amplified sounds from the hearing aids. The sounds escape through the vent and leak from the edges of the dome or the earmold.

Hearing aids earmolds and domes have vents so that wearers don’t feel like their ears are plugged. The vents also allow sounds to enter and reach the eardrum directly, without being amplified by the hearing aids. When ambient sounds mix with amplified sounds, they can produce interference, also known as the comb filter effect. The direct and amplified sounds aren’t synchronized, so they alternate between adding and cancelling each other out. That causes sudden spikes and drops in the combined signal, which look like the teeth of a comb (see figure 1).

More ventilation creates a bigger comb filter effect, which can affect sound quality.

In order to limit the impacts of the variability of the vent effect, a hearing aid manufacturer has integrated solutions directly into its hearing aids’ programming software. One of these solutions is to measure the Feedback Test. This ensures greater accuracy of the hearing aid programming and improves sound quality by measuring and compensating for the vent effect, individual to each person.

As mentioned, the comb filter effect is caused by direct and amplified sounds that are out of sync with each other. Sounds fall out of sync with each other because hearing aids can’t process sound instantaneously. They need time to capture, analyze, and amplify the sound for the wearer. Hearing aid wearers can perceive processing delays greater than 0.5 millisecond, which can lead to a distorted hearing experience.

That’s why one hearing aid manufacturer developed a new ultra-fast sound processing technology. It minimizes processing delays and eliminates the audible artifacts and distortion inherent in hearing aids until now. This innovation will improve the sound quality of hearing aids and make communication easier.