Using Research to Fill in Clinical Gaps: A Summary of Recently Published Hearing Research

by Brian Taylor, Editor-at-Large

Brian Taylor, AuD

Gamblers, paramours and clinicians all deal in uncertainty. No matter which of those groups you belong, you make better decisions when relevant and timely information, based on sound scientific principles, is available. Sometimes you might even find a kernel of truth that changes your outlook or behavior.

Here are five recently published studies that could make things a little more certain next time – either in-person or remotely – you’re in front of an adult with hearing loss. 

Revising Your Adult Hearing Aid Selection and Fitting Protocols

To find the most current evidence-based guidelines for selecting and fitting hearing aids on dults, you must go back more than a decade, to 2006.  Since then, of course, more well-designed studies have been conducted, more interventions have emerged and more features have been added to hearing aids, leaving those 2006 guidelines still useful but somewhat antiquated. Although the well-publicized Aging and Cognitive Health Evaluation in Elders (ACHIEVE) study, which is evaluating the impact hearing interventions might have on cognitive decline won’t be complete until 2020, workaday clinicians can still benefit today from this important study. 

As part of the design of the ACHIEVE study, researchers developed and vetted an evidence-based clinical protocol in which participants of the hearing intervention part of their study completed. Their evidence-based protocol, summarized below, could serve as a sensible template for any clinician.

Relying on a panel of experts, Sanchez et al devised a comprehensive hearing intervention protocol including the following elements along with specific tests and procedures for each: 

This protocol was used with 21 adult participants and 9 communication partners over the course of 24 weeks and seven visits to the clinic. Results showed that 20 of the 21 participants completed all seven in-clinic sessions. Outcomes, obtained at week 24, indicated participants received significant improvement in the aided condition, with the average unaided Quick SIN score improving from 11.8  to an aided average score of 5.3, and a reduction in hearing handicap as measured on the HHIE-S from 25.1 (unaided) to 6.1 (aided). Further, hearing aid benefit as measured on the COSI showed significant improvement, while data logging indicated 7 to 8 hours of daily use, on average. The authors also showed that all elements of this best practice protocol could be conducted in a timely manner, as most appointments were completed between 30 and 60 minutes.

Given the reasonableness of the time frames to complete the appointments, the generally excellent patient outcomes and the compliance of the participants to complete the entire intervention, clinicians would be wise to adapt these elements into their own best practice approach. 

Predicting Hearing Aid Success with the Revised Performance-Perceptual Test

Most clinicians agree that it’s beneficial to utilize pre-hearing aid fitting tests and procedures to predict hearing aid success with hearing aids. After all, it is fairly well established that many persons with hearing loss who are obtaining hearing aids for the first time want to know how much benefit they will receive from their investment of time and money. Even though there doesn’t yet exist a universal definition of hearing aid success, many clinicians use speech in noise testing scores to predict success. 

Several years ago, Saunders and Forsline created the PPDis as a way to bring rigor to the prediction of hearing aid success. Recall the Performance-Perceptual Discrepancy (PPDis), which relies on the HINT to conduct the Performance-Perceptual Test, identifies patients who are likely to overestimate or underestimate their ability to understand speech in noise, widely believed to be a key metric of hearing aid success. Once an under or over-estimator is identified the clinician can counsel them in a more precise way and perhaps make better predictive statements to individuals about their success with hearing aids. Unfortunately, few clinics use the HINT, therefore virtually no one uses the PPDis.

In a recent JAAA article, however, Ou and Wetmore used the more commonly available QuickSIN to find the PPDis. They compared PPDis results using the HINT to the QuickSIN and determined through their analysis that the QuickSIN is a valid replacement for the HINT. Thus, clinicians, many of which are already using the QuickSIN or have it readily available on their computer-based audiometer, have an additional data point, the PPDis score, to make predictions about hearing aid success. 

Determining Patient Readiness for Hearing Aids

It doesn’t take long for new clinicians to realize that hearing aid candidacy as defined by the audiogram is not equated with readiness to wear hearing aids. Research, in fact, suggests that about half of people  recommended hearing aids during a routine consultation appointment fail to obtain them.

Because the audiogram is a poor indicator of readiness for hearing aids, other approaches to determining patient readiness have been proposed over the years. One such approach relies on the transtheoretical stages of change model.  Many of the tools archived at the Ida Institute are based on this model of behavior change. Although the tools have been validated, clinicians by and large have not embraced them because it requires time to learn a new clinical procedure.

Ekberg and Barr, two Australia-based researchers who have focused several studies on person-centered care, evaluated the use of Ida Institute Motivation Tools to help clinicians identify patients who are ready to wear hearing aids. In their recent study, published at the International Journal of Audiology, they were able to successfully train five audiologists in about an hour how to use the Ida Circle and Line tools with first time help seekers. The researchers determined the audiologists were able to effectively use the Ida Tools as conversation starters and they contributed to learning more about what stage of change patients were in during their appointment. Clinicians looking to add a new wrinkle to their clinical approach with first time help seekers will find this article helpful. 

Extended Bandwidth, Maybe Not So Unsexy After All 

If you were fitting hearing aids 25 or more years ago, you may remember the original K-Amp hearing aid. It was probably the first hearing aid with an extended bandwidth beyond the standard 4-5KHz bandwidth of other devices available at the time. The problem, of course, because digital feedback cancellation didn’t exist yet was the extended bandwidth K-Amp was prone to feedback. Soon after, cochlear dead regions, which some experts suggested required patients who may have them to use hearing aids with restricted bandwidth, became popular to chase in the clinic and extended bandwidth as a potentially helpful special feature fell out of favor. 

Over the past several years, extended bandwidth has been making a quiet comeback of sorts. A wide range of manufacturers now offer hearing aids with extended bandwidth, but clinicians are more likely to get excited about wireless Bluetooth connectivity, bilateral beamforming and remote finetuning. Could it be that extended bandwidth, a rather ordinary feature that can be added to a modern hearing aid with a simple mouse click, benefits many of our patients? 

A recent study from researchers at Western University in London, Ontario, attempted to answer this question. The researchers fitted 24 study participants with a pair of hearing aids with two separate settings: extended bandwidth (10KHz) and restricted bandwidth (4.5KHz), similar to that found in conventional hearing aids. The researchers used commercially available probe microphone equipment and standardized procedures to verify that a DSL target was matched at frequencies above 7KHz in the extended bandwidth condition. 

Results showed that gain for average level inputs was achievable at 7.8KHz in the extended bandwidth condition. Improved perception of /s/, /z/ and /t/ phonemes was achieved with the extended bandwidth condition. About 80% of the participants either preferred the extended bandwidth setting or had no preference. These improvements in the extended bandwidth condition came with a limited downside as no significant changes in loudness perception or preferred listening levels were found. The study suggests that hearing aids with extended bandwidth provide several perceptible patient benefits with limited negative consequences for hearing aid wearers with mild to moderate, sloping hearing loss. 

Hearing Loss and Balance Link

South Korean researchers used their national healthcare database to examine the relationship between hearing loss and postural instability in adults aged 40 years and older. In their analysis of 3864 individuals, the researcher determined the presence of moderate or worse hearing loss was associated with increased odds of postural instability, probably not a surprising finding for clinicians working with older adults with hearing loss.

The link between balance problems and hearing loss held even for patients with unilateral hearing loss.

Their results, published in a recent issue of JAMA-Otolaryngology, make a case for screening the hearing of all adults presenting to a clinic with balance issues, and conversely, fall risk assessment ought to be completed on all adults presenting to the clinic with hearing loss. This study is yet another in a long line of recent research indicating that hearing loss needs to be considered beyond its impact on daily communication and its implications on overall health and wellness need to be evaluated more broadly.