Hearing aids are essential for individuals with permanent hearing loss, offering a primary solution to improve their hearing. These devices are customized to the user’s specific hearing needs, which are determined through an audiogram. An audiogram is created by having the patient listen and respond to pure tones, with the softest sounds they can hear plotted by frequency and decibel on a graph. This crucial information is then used by hearing aid manufacturers to develop a “hearing aid prescription.” There are proprietary prescriptions created by manufacturers and gold-standard, clinically validated audiogram-based prescription methods available to ensure optimal hearing aid performance.
Hearing aid prescriptions have a rich history dating back to the 1940s when Jones and Knudsen pioneered the audiogram mirroring procedure. Subsequently, Lybarger introduced the “half-gain rule,” where every 2dB of hearing loss was compensated with 1dB of gain. Over the years, research in hearing aid prescriptions continued to evolve, leading to the development of widely used fitting methods such as NAL-NL2 and DSL, which remain standard practices today.
With the introduction of over-the-counter hearing aids, it raises a crucial question: Are audiogram-based hearing aid prescriptions still necessary? Do these tailored prescriptions truly offer superior outcomes compared to users selecting their own settings? A systematic review conducted by Almufarrij, Dillon, and Munro, titled “Do we need Audiogram-based prescriptions? A systematic review,” aimed to explore this very topic.
For their review, they performed a database search of research articles. After removing duplicates, they located 412 potentially relevant records. After further review and screening, the authors were left with 7 articles for inclusion. The 7 articles utilized three different approaches to compare self-fitting to audiogram based fittings (1): comparing different settings based on Audiologist expertise, (2) client choice, or (3) client self-fit.
When comparing the settings based on Audiologist expertise, the authors “found no difference between the fitting approaches for self-reported benefit or for speech intelligibility in quiet but speech intelligibility in noise was significantly higher for the audiogram based approach”. In the studies where the client choice in sound was utilized, the authors noted that there were no significant difference in outcomes when compared to an audiogram based fitting. Finally, when the self-fit outcomes were compared to audiogram-based fittings, one study revealed that the participants significantly favored the self-fit settings and sound quality.
The authors comment “the findings of this review suggest that using a prescription with the individual’s audiogram is likely to improve outcomes relative to the comparative and client choice fitting approaches. For the client choice approach, the improvement is equivalent to about one quarter of the total benefit of acquiring hearing aids. Self adjustment during daily use may, however produce equivalent (or better) outcomes that an audiogram-based prescription. There is a need for more research into the topic now that OTC hearing aids are available on the market which are aimed to increase access to hearing healthcare. The authors also commented “it should be noted that the cost associated with the client choice and self-git approached is expected to be significantly lower than that of the individualized audiogram-based prescription approach with real-ear probe-tube verification, given that the former approached do not require the present of an audiologist or the use of advanced equipment”. These findings highlight the potential for more affordable and accessible hearing healthcare solutions, particularly as OTC hearing aids become more prevalent in the market. Future research will be crucial in understanding the long-term efficacy and cost-benefits of these diverse fitting approaches.
Dr. White, AuD 