Another situation where external factors are beyond the control of the hearing aid wearer is in the car. External noise is again a factor, but what distinguishes the car environment from a noisy restaurant is the near-complete absence of visual cues. Regardless of seating arrangement, visual cues are lacking, and speech can often be directed away from the hearing aid user. Without visual cues, hearing aid users cannot use speechreading, which has been shown to provide an additional 4-6 dB SNR improvement in noisy environments. Without visual cues, the patient is already at a disadvantage. The hearing aid user may be at additional disadvantage as the seating arrangement may result in a severely reduced speech signal, either because the hearing aid user is seated behind the target speaker or due to physical obstructions between the speaker and the hearing aid user.

Beyond the lack of visual cues and reduced amplitude of the desired speech, road noise presents another issue. Not only does driving introduce added noise, but the added noise may trigger a directional microphone setting in the user’s hearing aids, making it more difficult to understand the speaker or forcing the hearing aid user to turn his or her head towards the target speaker—which is especially not desirable if the hearing aid user is the one driving!

Remote microphone technology can offset the loss of visual cues by bringing the target speech in clearer and directly to the hearing aids. As noted before, the performance of remote microphone technology is a significant improvement in noisy environments over hearing aids alone, providing more SNR benefit than visual cues alone or directional microphones can. As an improvement over ReSound’s Mini Mic, ReSound’s Multi Mic provides additional noise reduction by entering a “Directional Mode” when worn vertically in the presence of noise. The directional response is directed towards the speaker’s mouth to preferentially amplify their voice, while not impacting other aspects of the hearing aid sound processing. The microphone can be clipped on the target talker (see image) or passed among multiple talkers, keeping the hearing aid user connected to the conversation even if someone is speaking from the back or a side seat of the car. It can also dramatically reduce the hearing aid wearer’s need to turn towards the talker—which means one less distraction for the driving hearing aid user.

A THIRD COMMON EXAMPLE; Listening At A Distance.

Listening from a distance presents its own challenges for hearing aid users. Typically, listening at a distance introduces some degree of reverberation, due to the size of the room, lecture hall, or place of worship. Similar to the car environment, listening at a distance effectively negates the benefits of visual cues, as the hearing aid user likely is not sitting close enough to take cues from the speaker’s face.

The final challenge is the most obvious: the speaker will sound softer to the listener than a typical face-to-face conversation. As the Inverse Square Law dictates, the SPL of any sound will decrease 6 dB with the doubling of the distance from the sound source. Given the size of many places of worship and lecture halls and the possibility of sitting in a new spot each week, the hearing aid user may be receiving a severely lower input compared to the initial signal. Most places of worship have sound systems, but can result in additional issues for the hearing aid user. Many lecture halls or classrooms do not utilize a sound system.

Remote microphone technology can alleviate the strains associated with listening at a distance, because the sound is brought directly into the hearing aids from near the speaker’s mouth—negating the reduction in volume and the addition of reverberation. Multiple studies have shown that the benefits of remote microphone technology do not dissipate when the distance between the remote microphone and the hearing aid user is increased, as long as it is within the working range of the remote microphone transmission protocol. The aforementioned research by Rodemerk and Galster shows that remote microphone technology provides significant improvement in speech perception in noise compared with hearing aids alone, even at a distance of 12 feet.

Research by Jespersen took that one step farther—well, actually several steps farther —by testing the ReSound Mini Mic, which utilizes 2.4 GHz wireless technology, testing the technology at 6 meters (almost 20 feet). They found no significant drop-off in performance in speech perception in noise when compared to shorter distances using the remote microphone technology. This research also found that the remote microphone significantly outperformed hearing aids alone —even in a directional microphone setting at these distances. With the ReSound Multi and Micro microphones, the range is increased so the target speaker can be up to 30 meters (>90 feet) away from the hearing aid user and within a clear line of sight, and the patient can still receive the benefits of the remote microphone technology.