Keeping up with technology can be a challenge in today’s world of hearing instruments. Imagine this scenario: The hearing aid manufacturer adds a new line of devices or changes the fitting software. Now you are in a hearing aid fitting and you see features and settings that you don’t recognize. Of course this is not too hard to picture because it is part of being an audiologist and fitting hearing aids. Audiologists are specialists in the physiology of hearing and patient care. But in addition, they are expected to be technical experts in fitting hearing instruments, and pros at navigating clever marketing names. Here are a few tips and tricks to assist Super-Audiologists in their hearing aid fitting endeavors.
Gain vs display
Several features and facets in ReSound Aventa modify insertion gains and gain targets; these include patient experience level, device configuration and target rule selection. However, some only change the display of the targets (i.e., changes to the venting or tubing found in the Physical Properties section). Display changes are designed to give the fitter a better idea of how much gain they can expect in the average ear canal for a particular ear coupling, or in other words, what to expect if they verify the fitting through real ear measures. ReSound offers several devices that have multiple configurations based on the receiver, in the case of an receiver in the ear (RIE), the openness of the device, or the power level. Completing a confirmation change in the fitting software, or a “reconfigure,” will actually change the gain targets, not just the display. Below are right and left ears fit with the exact same hearing instrument with the right configured as open and the left configured as closed with corresponding coupling choices. Is this merely a display change, or a true gain target change?
As an investigation we conducted coupler measurements of RIE devices from several different manufacturers, programmed with the same audiograms and the most open configuration and vent settings. We then programmed the instruments with the most occluding options and measured again. The measurements revealed that some settings affected the gain and others did not. We noticed that the seven tested settings fell into groups of three different approaches.
Three approaches were noted when changing from open to closed across the manufacturers’ RIE fittings:
- Nothing- gain was not affected
- Less gain for open- prescribed more gain for closed configurations across frequencies due to more usable low frequency gain and compensation for the lost canal resonance
- More low frequency gain for open- Low frequency gain is boosted for open fittings, in an attempt to compensate for roll off, and high frequencies are reduced for canal resonance
Changes made to the “Physical Properties” in ReSound Aventa and “Acoustic Options” in Starkey Inspire kept gains consistent when switching from open to closed fittings. The “Reconfigure” option in ReSound followed the second approach. Oticon “Acoustics”, Phonak “Acoustic Parameters” and Siemens “Acoustical Parameters” adhered to the third approach. Changing the physical coupling to the ear and not setting, or incorrectly setting, these features in the fitting software may drastically impact the fitting. The message here is this: Manufacturers differ in how these options are treated in fitting software. Know your manufacturer, or if you are unsure of what changes are made through these settings, double check that they are set appropriately every time. The good news is that if you are ever in doubt, you can always verify the fitting and get to the bottom of it once and for all.
Stay tuned for the next edition of “Tips and Tricks for the Super-Fitter”!