Is the Audiogram Needed to Fit Hearing Aids?

Author: Brian Taylor, Au.D.

All clinicians can agree that comfortable, natural sound from hearing aids is a reasonable first-fit starting point for anyone wearing them. However, does the audiogram need to be part of the equation when it comes to the first-fit starting point? That notion is being called into question by scientists involved in the creation of self-fitting hearing aids.

Although most clinicians don’t complete all the steps outlined in many best practice protocols, they have relied on the prescriptive method to fit hearing aids for more than 30 years. Now, that process, which requires, at a minimum, clinicians enter a patient’s hearing thresholds into computer-based fitting software is being challenged.

In a paper published January 31st at the open access journal, Trends in Hearing, researchers demonstrated adults with mild-to-moderate hearing loss could select hearing aid parameters similar to those derived from a vetted prescriptive approach, such as NAL-NL2.

In their study, conducted at Northwestern University’s hearing aid clinic, a group of 75 adult patients with mild-to-moderate hearing loss were split into two groups. One group wore hearing aids with acoustic parameters, selected by an audiologist following conventional best practice prescriptive fitting methods and the ability to adjust gain-only in the device, while the second group wore a device allowing them to directly self-adjust many of the hearing aid’s acoustic parameters using a smartphone-like interface.

After the entire group of 75 participants were initially first fit using conventional prescriptive methods and allowed to wear the prototype hearing aid for about one week as a practice session, they returned to the clinic for some fine-tuning, and then split into the two groups. The “audiologist selected” group left the clinic for a 30-day at-home trial with gain set to closely match their prescriptive target and the ability to adjust gain-only (+/- 8 dB) using the smartphone-like interface. In contrast, the “self-fit” group left the clinic for the 30-day at-home trial with a starting point of 0 dB insertion gain (REIG) and the ability to self-adjust two sliders on the smartphone-like interface that were tied to compression, gain and frequency response parameters of the hearing aid. During their at-home trial, both groups were able to randomly report, using a real time assessment feature on the hearing aid, their satisfaction with sound quality during various types of listening situations. At the same time, the researchers were able to record the participants’ hearing aid settings when they made their self-reports.

At-home use of the devices showed, regardless of the group, that participants with greater hearing loss selected greater amounts of gain, with the “self-fit” group selecting slightly lower amounts of gain compared to the “audiologist-selected” group. Further, preferred gain levels for both groups were remarkably similar. The deviation from the initial prescriptive starting point in the clinic was calculated two different ways: Overall gain and gain per band. The gain selected by the “self-fit” group was within 1.8 dB for overall gain and 5.6 dB per band, on average, compared to the gain selected by the audiologist at the initial fit in the clinic.

While wearing the devices, participants were able to make A/B comparisons between their own self-selected parameters and those selected by the audiologist, during the initial fit in the clinic. Both groups preferred their own self-selected settings more than the settings they received during the initial fitting in the clinic, but the preference for their own self-selected fitting was stronger for the “self-fit” group. Following the at-home trial, a series of standardized measures of outcomes were conducted in the clinic on all participants following their at-home trial, including the APHAB, SSQ-12 and aided QuickSIN. The average scores on these outcome measures did not differ between the two groups, as both groups derived benefit from their respective fitting approach.

Given the similar preferred gain settings and outcomes between the “self-fit” and “audiologist-selected” groups, the researchers surmise that adults with mild-to-moderate hearing loss, when provided user-friendly tools, can successfully fit their own hearing aids with minimal or no involvement from an audiologist. Also, it’s worth considering that the fitting method employed in this study possibly could be used by patients with severe or asymmetrical hearing losses – groups that were not included in this study, but nevertheless should not be precluded from such a fitting approach, simply because they have more complex hearing loss.

Considering the remarkably similar outcomes between the two groups in this study, consumers may soon have a choice between two different fitting procedures: one driven by the clinician, using traditional threshold-based principles, and another that places the control firmly in the hands of the wearer. Audiologists must be poised to work with both types of persons with hearing loss: those who want in-person assistance and those that choose to self-direct their care and begin the process of improved communication by self-fitting their own hearing aids. Indeed, evidence is emerging that both approaches lead to successful outcomes.