Hearing aids need to be set up for the user’s specific hearing loss and ear canal resonance. How do we do that?
Real Ear Measures
Most governing professional regulatory bodies mandate that hearing aids are fit using “real ear measures” or REM for short. Simply put, REM is a process whereby we take the hearing test from the booth, apply a mathematical formula or algorithm to the test that determines how much volume (“gain”) to apply for soft, medium and loud input sounds. We then place a microphone tube deep down the ear canal to measure what the hearing aid is producing for each of these three inputs. Not only that, it also deducts from the hearing aid amplification the natural amplification effects the resonance of your ear canal adds because of its size and shape.
What’s the big deal?
REM was a big deal in the 1980s when the hearing test, hearing aid and REM all used the same type of technology so it was like comparing apples to apples. Today, 40 years later, we still use REM, with “updated” algorithms that are now about 20 years old. This outdated math applied to high tech devices with so many features and functions that have to be turned off to run REM, therefore doesn’t give us a true measure of what the hearing aid is doing. Not only that, REM is invasive, the tubes can be uncomfortable and the “apples” of the ANSI (American National Standards Institute) test in the booth, coupled with the “oranges” of the new technology of hearing aids applied to the “bananas” of REM algorithms results in a fruit salad where we don’t really know if the hearing aids we’re fitting are correctly producing the sounds tested in the booth to begin with.
Why use REM then?
Real ear is a great tool for verifying if there is an issue, post-fitting resonance problem, or to troubleshoot sound artifacts and/or hearing aid function, but not to fit them and leave the settings as such. REM is the ONLY formal clinical procedure that can be mandated despite its shortcomings by a regulatory body to avoid poor fitting practices, and set the lowest common denominator for hearing aid fittings so that practitioners do the least necessary procedure, and so that the customer/public is “protected”.
What’s the Alternative?
Insitu Fittings
When you’re fit with a hearing aid today, REM may be done to check some things on the devices but will then be over-written by settings determined by another set of measures. The first will be a feedback/real-ear calibration which uses sounds to create a map of the resonance of your ear canal to avoid hearing aid squealing (feedback) and ensure that the amplification into your ear is appropriate once the next procedure is done. The second procedure is “insitu testing” where we do a visual, co-operative hearing test together on-screen where you determine when you start hearing the tones at each pitch at their softest level. This corrects for the differences between the hearing test in the booth and how the technology you’re wearing interprets each of those tones. Without that correction, we cannot verify that your hearing aids are working for you.
What’s the advantage of Insitu Fittings?
There are many advantages of insitu fittings. The biggest advantage is that you participate in the settings of the hearing aids. Furthermore, the original test is confirmed, your resonance still contributes to the calculation of how gain is set just like in REM, and the devices’ intrinsic differences in their electronic components is accounted for.
Why does this matter?
Most Hearing Instrument Practitioners and Audiologists are mandated to do REM which tells the hearing aid how to work. These settings are often harsh, loud and uncomfortable for the user. Most clinicians will not disclose, inform or advocate either way and likely not give the patient/client/consumer an option as to how the hearing aids are fit. Many great voices in the Audiology field strongly recommend REM but it is a starting not ending point and it is a great troubleshooting tool, no longer the gold standard for optimal hearing aid adjustment.
As a consumer, you have the right to consent to care, whether REM or Insitu, and can equally not consent to either. Get your hearing aid fit so that how it is designed and what your ear and hearing requires are both part of the fitting.