Personally, I really like to develop hearing aids and audiological solutions for people with severe-to-profound hearing loss since I see it as the most challenging and audiologically demanding category. One could say that this is the supreme discipline of audiology when it comes to hearing aids. I also find it most rewarding to help these people who are so dependent on their hearing aids in their daily life. For them, a great hearing aid fitting can really make an outstanding difference in their quality of life.
Fitting hearing aids to people with severe-to-profound hearing loss may not be your daily business. For example, only an estimated
6.7 % of the local clinical population in the United Kingdom National Health Service clinics was found to have a hearing loss higher than 70 dB averaged across 0.5, 1, and 2 kHz (Smith & Turton, 2013). This number lies nicely in the range of 5 – 10 % that I commonly hear when I talk to either my students or my colleagues.
The reasons for a severe-to-profound hearing loss are diverse: people are born with a significant hearing loss, it may be acquired from an illness such as measles or bacterial meningitis, it can be a side effect from ototoxic medication, high noise exposure, or physical trauma, or due simply to the process of aging. Because of this diversity, the age of such people in this group can vary a lot.
What they have in common is that they face many obstacles in managing their communication, even in quiet and especially in noisy environments. And listening effort is higher than those with no or mild hearing loss. This can result in exhaustion at the end of the day.
From an audiological perspective, there are some important characteristics of this category of hearing loss:
- the vastly reduced audibility which is visible in the highly elevated hearing thresholds,
- the narrow residual dynamic range (even if the Uncomfortable Loudness Level (UCL) is not measurable, due to the limits of the audiometer),
- the frequency and temporal resolution are probably reduced which may affect speech recognition abilities (Moore, 2014).
All of this is probably a consequence of the loss of not only outer hair cells but also inner hair cells which degrades the possibility of the cochlea to resolve complex signals.
Consequently, the hearing aid must provide enough audibility. This requires sheer amplification and high gain, and output values with low distortion. Feedback cancellation systems are very important to provide a feedback-free listening experience. Also, frequency lowering technology is essential to provide access to speech cues in the higher frequency area due to the likely presence of dead regions in the cochlea.
The narrow dynamic range means that people with severe-to-profound hearing loss are very sensitive to small level changes. A hearing aid for this category should offer small increments in dB when it comes to the volume control. It is important that the hearing aid provides high sound quality so as not to degrade the perceived quality of the incoming signal. Since these individuals rely heavily on the speech envelope, it is important to have a compression system at hand that preserves that crucial envelope information as well as possible.
But even with the best hearing aids, conversations in noisy environments are still extremely challenging. As a rule of thumb, one could say that the greater the hearing loss, the higher the signal-to-noise ratio (SNR) required to follow a conversation. This sometimes requires additional devices such as remote microphones.
For providing the best audiological solution and power in a hearing aid, we developed the Leox Super Power and Ultra Power BTE instruments. With the industry’s highest peak gain of 87 dB and 146 dB maximum output, the Leox Ultra Power allows for the audibility that is needed, supported by a great dynamic feedback cancellation system (Lesimple, Kuriger, & Künzle, 2019) and a well-known frequency lowering technology (Kuriger & Lesimple, 2012). A wide range of features and many connectivity options are available, to ease communication in noisier environments. And, of course, fitting these hearing aids requires a knowledgeable HCP who knows about the audiological and practical needs of this user group.
Give Leox a try the next time a customer with a severe-to-profound hearing loss seeks help.
For more information about Leox 7|3 Super Power | Ultra Power hearing aids, go to www.bernafon.com/products/leox.
References
Kuriger, M., & Lesimple, C. (2012). Frequency Composition™: A New Approach to Frequency-Lowering. Bernafon White Paper, 1-8.
Lesimple, C., Kuriger, M., & Künzle, B. (2019). Reduced acoustic feedback in realistic and active situations with Dynamic Feedback Canceller™. Bernafon White Paper, 1-8.
Moore, B. (2014). Auditory processing of temporal fine structure. World Scientific, Singapore.
Smith, P., & Turton, L. (2013). Prevalence & characteristics of severe and profound hearing loss in adults in a UK National Health Service clinic. International Journal of Audiology 52(2), 92-97.