After completing this course, readers will be able to:
- List the three acoustic challenges that limit the performance of hearing aids in everyday situations.
- Explain two ways in which aspects of a hearing aid ecosystem can contribute to benefit with telephone use.
- Give three concrete examples of situations where a wireless hearing aid accessory could solve a difficulty experienced by the hearing aid use.
After boarding a recent flight to San Francisco, the man in the seat next to the first author launched the typical “airplane” conversation: Are you traveling for business or pleasure? She explained she was traveling for business, and that she worked for a hearing aid company. As the man was wearing hearing aids, it was not surprising that he followed up her response with observations about his hearing.
In our profession, we have all been in a similar situation. The good news is that this hearing aid user was generally satisfied with his hearing aids. He actually said his hearing aids had been life changing. He was able to communicate now at work, and he had been having significant trouble in his work environment before he was fitted with hearing aids.
However, he went on to say he wished his hearing aids would do a better job in noise. In particular, he mentioned enjoying dinners out with his wife, but that he often could not hear her in restaurants. He also stated that both the TV and the telephone presented hearing challenges from time to time. A close look at his hearing aids revealed and they were wireless, meaning they could be fitted with an assortment of accessories to improve hearing in these difficult, noisy situations. When asked if his hearing care professional (HCP) had ever told him about the accessories that could be used with his hearing aid, he did not recall hearing about them. But during that flight, he was very interested in learning all about them.
We will never know what happened after that flight with this friendly fellow passenger and his hearing aids. Yet as members of this health profession that strives to provide the best hearing possible for our patients, we hope he returned to his HCP to obtain some accessories. If he did, he would find that he could hear his wife in restaurants better. He might find that his enjoyment would increase and his stress levels might decrease in noisy, difficult environments, based on being able to hear more clearly and effortlessly. He might also find it much easier to hear television programs and more confidently take phone calls.
Despite all the improvements in hearing aids through the years, there are still situations where hearing aid users have difficulty when using hearing aids alone. These situations include any of the following factors: background noise, listening to a talker over distances, and reverberant spaces. None of these problems can be alleviated fully with hearing aid signal processing and features alone. It is for that reason assistive listening devices such as FM systems and hearing aid wireless accessories were developed. The good news for hearing aid users is that these assistive listening devices are designed for the sole purpose of addressing these common listening challenges. This good news translates to user benefit – but only when the user is fitted with a hearing system including FM or wireless accessories, not merely with hearing aids alone.
What do we mean by hearing ecosystems? An ecosystem is defined in this context as an interconnected system of components, working together. The modern hearing ecosystem shown in Figure 1 provides benefits beyond those provided by a hearing aid alone. At the center of the system is the hearing aids, which largely control the function of the accessories and everything else. Wireless accessories include microphones, TV streamers, remote controls, and a phone accessory for Bluetooth-enabled phones. The system in Figure 1 also includes a direct connection to Apple iPhones and other Apple devices, with the additional use of apps for controlling the hearing aid or helping with tinnitus. For ease and convenience during fittings and follow-up visits in the clinic, a wireless programmer is included in the system. The most recent addition to this particular hearing system is a teleaudiology option, which can be used to provide an unprecedented level of personalization and patient care. Yet the wireless accessories play a fundamental role in the ecosystem, augmenting the desired signal for hearing aid users in the situations that continue to challenge them the most.
Figure 1. The ReSound LiNX 3D Ecosystem.
What is the Evidence that Accessories are Beneficial?
Realistic expectations have been a large part of hearing aid counseling for decades. Hearing care professionals tell patients that hearing aids will not solve all of their hearing problems. This is correct; hearing aids do not allow hearing aid users to hear optimally well in all environments. Hearing aids have a hard time overcoming the three challenges listed above, concerning hearing in noise, hearing in reverberant environments, and hearing from greater distances. Hearing on the phone is another classic problem with hearing aids, as visual cues are missing, the phone signal has restricted bandwidth, and optimal placement of the phone relative to the hearing aid can be tricky and tiring to maintain.
The universal solution to these problems is to improve the signal-to-noise ratio (SNR). While hearing aids can improve the SNR up to 3 or 4 dB using their built-in directional microphones (Bentler, 2005), they cannot compare to the dramatic boost in SNR provided by picking up the signal of interest at its source. Assistive technologies such as FM systems have been used to this end for years to overcome the negative effects of a poor SNR or considerable distance from a speaker. There have been many studies documenting the benefits of FM systems in these difficult environments. For example, Lewis et al (2002) investigated speech understanding in noise for 46 adults when using BTE hearing aids with directional microphones, and the same hearing aids coupled to personal FM systems. Results showed, on average, that the directional microphones on the hearing aids improved the reception threshold for sentences (RTS) by 3.4 dB over an omni-directional condition. In the FM condition, however, the RTS improved by 19.3 dB over the directional condition, and 22.7 dB over the omni-directional condition. This amount of benefit cannot be achieved by hearing aid directional microphone technology alone.
While FM systems have been proven to effectively improve SNR, they are expensive. In addition to this hurdle, FM systems still require FM receivers to be worn by the user, which continues to limit the use of the technology for most adults. Finally, traditional analog FM technology is susceptible to interference and does not provide privacy in transmission. As an alternative, digital wireless microphone accessories work together with hearing aids to improve the SNR in a similar way to FM, but cost only a few hundred dollars. In many cases, the user can receive the SNR benefits of a wireless microphone accessory without needing to wear a special receiver apart from the hearing aids themselves. Transmission of the signal is quite robust to interference and cannot easily be intercepted by devices that are not specifically paired to the transmitting microphone.
The question then turns to how well today’s wireless microphone accessories perform.
Rodemerk and Galster (2015) compared the benefit of four microphone accessories in four test conditions. The results showed that all four microphones accessories helped users perform better in noise than hearing aids alone. For the wireless microphone-only conditions, all four remote microphone systems yielded speech recognition scores that were 11-15 dB better than unaided and hearing aid-only conditions. There were no significant differences among the four remote microphone systems. Further, this pattern of results was consistent when the listener was 6 feet and 12 feet from the loudspeaker.
Jespersen (2012) tested the speech reception thresholds (SRTs) of hearing impaired listeners in 3 conditions: adaptive directional microphone hearing aids, ReSound Mini Microphone accessory with the hearing aid microphones off, and ReSound Mini Microphone accessory with the hearing aid microphone activated. The SRTs were measured at three distances within the 7 meter wireless range of the accessory, at 1.5, 3 and 6 meters from the speaker. Figure 2 shows the results of the study. The ReSound Mini Microphone provided significantly better SRTs than hearing aids with directional microphones alone, with the greatest difference when the hearing aid microphone was off. At increased distances, the hearing aid-only directional benefit decreased quickly, while the benefit for the ReSound Mini Microphone conditions was stable, even at 6 meters.
Figure 2. Average SNR benefit, shown as the SRT score, for the ReSound Mini Microphone wireless accessory and directional hearing aids alone when the speaker was 1.5 m, 3 m and 6 m from the hearing aid user. More negative SRT scores indicate better performance; the scale on the y-axis has been flipped to show better scores at the top of the graph. From Jespersen (2012), reprinted with permission from Hearing Review.
The more recently introduced ReSound Multi Microphone and ReSound Micro Microphone are equipped with directional microphones, unlike the ReSound Mini Microphone accessory used in this study. As a follow-up to the previous study, Jespersen and Kirkwood (2016) compared the SNR improvement of the ReSound Multi Microphone to directional hearing aids alone, the ReSound Mini Microphone, and a built-in microphone solution on a mobile phone. Results showed the ReSound Multi Microphone provides 15 dB more SNR improvement than what hearing aid directionality provides. The directionality also provides a significantly better SNR improvement (5 dB) than the earlier ReSound Mini Microphone, as well as the built-in mobile phone microphone solution.
The final validation of current wireless microphone accessories: how do they perform when compared to the traditional “gold standard” SNR benefit provided by FM systems? The Jespersen and Kirkwood study also revealed the SNR improvement for the ReSound Multi Microphone was equivalent to that of a current, modern FM system. Regardless of how the FM system was coupled to the hearing aids, via an external receiver and DAI boots, or as an attachment to the DAI port of the ReSound Multi Microphone which would then stream the FM signal directly to the hearing aids, the SNR improvement for all conditions was around 22 dB. There were no statistical differences among the conditions tested, meaning wireless accessories can serve as a viable, convenient alternative to FM systems for SNR improvement. Patients may now have many avenues to better SNR benefit that fits into their own lifestyles – via a wireless accessory alone, via an FM system coupled to the hearing aids, or via an FM system coupled to a wireless microphone accessory such as the ReSound Multi Microphone.
Wireless microphones are only one accessory in hearing ecosystems. TV streamers and Bluetooth-enabled phone accessories provide SNR improvement as well, as they pick up the desired sound at its source. Since many hearing aid users report difficulty using the telephone with their hearing aids (Picou & Ricketts, 2013), a wireless streaming option can provide a much-needed avenue to better hearing on the phone. Wireless streaming of the phone signal to both ears also results in bilateral presentation of the phone signal, which has been shown to be beneficial for speech recognition performance as compared to traditional monaural phone use (Picou & Ricketts, 2011).
Smith and Davis (2014) studied the benefits of wireless accessories as part of a hearing system among test participants ranging in age from 22 to 79 years, with varying hearing losses and years of hearing aid experience. All subjects in the study were issued a phone streamer, a TV adapter and remote control. After the initial 8 weeks, the subjects were given a wireless microphone for streaming for the last 4-week period. Results for the Glasgow Hearing Aid Benefit Profile (GHABP) (Gatehouse, 1999) showed a significant increase in scores for benefit and satisfaction with the use of accessories. There was also a significant decrease in residual disability with the use of accessories. For the International Outcome Inventory for Hearing aids (IOI-HA) (Cox & Alexander, 2002), when comparing scores with hearing aids alone and using the accessories including the microphone, results showed significant improvements for 5 out of the 7 questions and the overall scores with the microphone accessory. This study was unique because the IOI-HA was administered three times: before accessory use, with the TV and phone accessory, and finally with all three accessories (TV, phone, and remote microphone). The third visit with the addition of the remote microphone showed the most improvement on IOI-HA scores.
The introduction of Made for iPhone (MFI) direct connectivity between supported Apple products and certain hearing aids in 2014 has provided even more opportunities for SNR improvement and subsequent user benefit. In a study by Jespersen and Kirkwood (2015), 15 listeners with severe-to-profound hearing loss were tested in several conditions: traditional use of the phone with hearing aids in an “acoustic phone” program (a monaural hearing aid condition), wireless phone accessory streaming to one hearing aid only, and MFI audio streaming to one hearing aid only. Speech recognition testing in this study showed significantly better performance for streaming the phone signal via the accessory or MFI streaming, as compared to monaural listening through the phone receiver and the hearing aid acoustic phone program (Figure 3). Since this study involved hearing aid users with severe-to-profound hearing losses, the improved listening on the phone was very noticeable.
Figure 3. Streaming of the phone signal to the hearing aid results in significantly improved performance in speech recognition testing. From Jespersen and Kirkwood (2015), reprinted with permission from Hearing Review.
The same study also investigated monaural acoustic phone use as compared to binaural streaming of FaceTime phone calls, via either a wireless accessory or MFI streaming. With the FaceTime application, users can hear and see the caller during the phone conversation, which provides visual cues for speechreading that are not present in a traditional acoustic phone conversation. As would be expected, the addition of the visual cues plus the binaural hearing benefits of the streaming of the FaceTime conditions yielded significantly better speech recognition scores than the traditional monaural use of the phone without visual cues (Figure 4).
Figure 4. Bilateral streaming of the phone conversation, with the addition of visual cues for speechreading made possible by the FaceTime app, resulted in significantly better speech recognition scores than traditional monaural aided use of the phone. From Jespersen and Kirkwood (2015), reprinted with permission from Hearing Review.
Listening in noisy conditions, over distance, in reverberant environments, and on the phone are ubiquitous difficulties for many hearing aid users. But the good news is that there is a solution to each of these common issues – the use of wireless accessories or other assistive technologies with hearing aids. Studies show clear user benefits and SNR advantages when FM systems, wireless accessories, apps such as FaceTime and/or MFI streaming are introduced as part of the user’s hearing care. The solution to the difficulties we still hear from today’s hearing aid users cannot be provided using hearing aids alone – a hearing aid system is necessary to achieve better listening across challenging, everyday situations.
Clinical Applications of Accessories
Integration of wireless accessories into hearing aid user’s lives can take many forms. Here are a few scenarios illustrating how the user can improve hearing in different situations via the options provided by a hearing system.
User #1 – Problem. “I drive across the country with my wife once a year and I can’t hear in the car well enough with my hearing aids to carry on a conversation. My hearing aids are even equipped with technology to pick up speech from different directions around me, and still I can’t communicate effectively."
Solution: His wife can use a remote microphone accessory to stream her voice directly to his hearing aids.
User #2 – Problem. “I have a smartphone but I only use it for texting. Everyone knows not to call me on it because I can’t hear well enough to communicate with them.”
Solution: Use a hearing aid that connects to an iPhone directly, or any Bluetooth-enabled phone using a phone accessory.
User #3 – Problem. “Even with my hearing aids, the speech on the TV isn’t clear. There is so much music and background noise on TV shows today that picking out the speech is difficult.”
Solution: Use a TV streamer; the SNR improvement over noise in the room will make it easier to hear the speech on TV shows.
User #4 – Problem. “Even with my top-of-the-line hearing aids, I can’t communicate in noise unless the person talking is right by me.”
Solution: Use a microphone accessory in noisy environments to stream the talker’s voice directly to the hearing aids.
User #5 – Problem. “I like to take walks in the evening but can’t hear my husband.”
Solution: As they walk together, her husband can use a wireless microphone accessory so she will be able to hear him better, even without being able to face him directly.
User #6 – Problem. “In my college lecture hall, I am having troubles hearing the professor because of the large size of the room and the echoes.”
Solution: Have the professor wear a wireless microphone accessory, and sit within the wireless range of the accessory.
User #7 – Problem. “I work with customers and colleagues in kitchen sales. I don’t know how a wireless microphone accessory would work for me, since I am usually talking to two or more people at the same time.”
Solution: Attach the microphone accessory to the end of the clipboard she carries with her to take notes. She can subtly direct the end of the clipboard in the direction of whoever is speaking at the time.
User #8 – Problem. “I like to take tours, but can never hear the tour guide very well, especially when we’re in loud spaces like museums, kitchens or factories.”
Solution: The tour guide can use the wireless microphone accessory and stream directly to the user’s hearing aids.
User #9 – Problem. “After the kids come home from school, I help them with their homework while my husband is in the kitchen cooking. I have never been able to hear him when he talks to me in this situation, especially since he is in a different room next to me. He always has to shout to get my attention, and I have to walk over to the kitchen to hear him.”
Solution: Her husband can use a wireless microphone accessory to communicate even while in different rooms.
User #10 – Problem. “I like to watch TV in bed before going to sleep, but my wife usually wants to fall asleep sooner than I do. She certainly can’t fall asleep at the volume level I need to hear the TV.”
Solution: A TV streamer accessory can allow the hearing aid user to greatly reduce or mute the volume of the TV while streaming the sound at the appropriate level to be able to hear – without disturbing others in the room.
As hearing care professionals, we strive to provide better hearing for our patients. Many of us make a point of informing about hearing systems and the benefits offered by augmenting hearing aids. Still we continue to hear about times when hearing aids aren’t quite getting the job done to the expectations of the individual. It is unrealistic to expect that users will request the extra help that is available to them once hearing aids are fitted. In fact, 70 to 80% of users don’t even realize that wireless accessories to their hearing exist (EHIMA, 2015). This isn’t necessarily because they weren’t counseled, but simply because it is normal to not retain much of what is communicated at a hearing aid fitting. Because their focus will naturally be on the hearing aids themselves in the initial phase, repetition and reinforcement of the hearing ecosystem concept is important for users to take best advantage of what their hearing aids can do for them. We would be so bold as to suggest that every hearing aid user could receive additional benefit from their hearing aids with the addition and use of at least one wireless accessory. And because the evidence in support of hearing ecosystems is so strong, these benefits will be clearly noticeable to users. We would recommend that continual consideration and counseling on how users can profit from the capabilities of modern hearing aid systems should be a part of clinical followup. As digital wireless technology has become nearly universal in basic as well as advanced hearing aids, hearing ecosystems have also evolved, to help us help others meet their rising expectations of better hearing in all aspects of daily life.
Bentler, R.A. (2005). Effectiveness of directional microphones and noise reduction schemes in hearing aids: A systematic review of the evidence. J Am Acad Audiol., 16(7), 473-484.
Cox, R.M., & Alexander, G.C. (2002). The International Outcome Inventory for Hearing Aids (IOI-HA): psychometric properties of the English version. Int J Audiol., 41(1), 30-35.
EHIMA. (2015). Eurotrak UK 2015. Retrieved from: https://www.ehima.com/wp-content/uploads/2016/02/EuroTrak_2015_UK.pdf.
Gatehouse, S. (1999). Glasgow hearing aid benefit profile: derivation and validation of a client-centered outcome measure for hearing aid services. J Am Acad Audiol., 10(80), 103.
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Picou, E.M., & Ricketts, T.A. (2011). Comparison of wireless and acoustic hearing aid-based telephone listening strategies. Ear Hear., 32(2), 209-220.
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Christensen, L.A., & Stender, T. (2017, November). Hearing ecosystems: How hearing professionals can meet the needs of today's hearing aid users. AudiologyOnline, Article 21652. Retrieved from www.audiologyonline.com