The Bottom Five Questions to Global Audiology

By Jennifer Groth

How many times have you gone to the Internet to research a topic or check your email, and been distracted by a headline such as “The five things guys notice”, “6 ways to look great in a bathing suit tomorrow”, and “Top ten reasons Yoda was actually dead all along”?

There’s something about titles with lists that seem to make them irresistible to click on. This month, we have plucked a brief list of some of the least asked questions we’ve had recently. One of the roles of Global Audiology at ReSound is to answer or track down answers to the more challenging of the many questions that audiologists have about our products, technology, fitting, or general hearing aid related topics. Some of these turn out to be quite fun, albeit in a “nerdy” sort of way, and it seems a shame for them to dead end with the person who asked them. Thus this month’s list:

Q1: My patient is picking up random cell phone conversations with her Verso hearing aids and she does not have any wireless accessories. What can I do about this?

A1: Cell phone signals are transmitted in a different frequency band than our 2.4 GHz wireless system. Apart from that, they are encrypted. Even if the hearing aids could receive a cell phone signal, our system cannot decode it. What can happen with hearing aids in the proximity of cell phones is that the signal causes interference that can be heard as a pulsing or buzzing noise by the hearing aid wearer. As many audiologists are aware, this is much less of an issue today, and both hearing aids and cell phones carry ratings indicating how well they can be expected to perform in terms of interference.

There is much information available on hearing aids and cell phone interference, including from the FDA (http://www.fda.gov/Radiation-EmittingProducts/RadiationEmittingProductsandProcedures/HomeBusinessandEntertainment/CellPhones/ucm116327.htm ) and ASHA (http://www.asha.org/public/hearing/Hearing-Aids-and-Cell-Phones/ )

For this question, we also researched whether it was possible for the Verso hearing aids to receive AM transmissions. Our theory was that perhaps this might happen when the patient was near a radio tower or in the path of walkie-talkies. To do this, the hearing aid was exposed to an AM signal in a controlled environment. While it was actually possible to generate an audible signal in the hearing aid, this only happened at extremely high field strengths that would not occur in real-life environments.

Q2: My patient says her Verso hearing aids are causing her handheld poker game to turn on.

A2: The hearing aids were suspected here because they send out wireless beacons that look for each other (in the case of device-to-device communication) or proprietary wireless accessories. Similar to the cell phone question, the hearing aids cannot communicate with devices that are not using the same proprietary wireless protocol. Apart from that, the game in question would have a mechanical switch that powers it off and on. The wireless beacons from the hearing aids cannot activate a mechanical switch. In this case, we suspect there was something faulty with the switch on the poker game.

Q3: Does ReSound buy their signal processing package from ON Semiconductor? I have heard that most of the major manufacturers do, and that there is thus no difference in their supposedly different algorithms.

A3: No, ReSound does not use any off-the-shelf solutions. We research and design our entire system in-house, including all signal processing.

Q4: My patient was just fit with Versos and a Phone Clip+. He also has a Bluetooth system in his car which he prefers to use when driving. If he gets in his car, the phone stays connected to his Phone Clip+. How do we get it to automatically go over to the car system?

A4: The Phone Clip+ is passive in its relationship to the cell phone, so it is not the accessory that is driving the connections but the other way around. If there is not intelligence built in to the phone that would allow it to prioritize and switch connection to a different paired device (and I’m not enough of a cell phone buff to know if this functionality even exists), then the user must manually choose the device he wants to be connected to.

Q5: What’s the difference between “binaural” and “bilateral”?

A5: The confusion here arises because most manufacturers refer to any signal processing that involves input from hearing aids fit to two ears as “binaural processing”. In contrast, all of the processing that is done on the basis of input to just one of the hearing aids is referred to as “bilateral”. So the term “binaural” is being used to indicate that there is some sort of cooperation between the hearing aids. Technically, however, “binaural” processing is that which is carried out in the central auditory system of a listener’s brain. The term “binaural” implies that hearing is involved, and hearing is done by the brain. ReSound attempts to use the term “binaural” in this sense, while using the term “bilateral” to refer to peripheral mechanisms or to anything referring to cooperative processing in the two hearing aids. The ReSound naming of “Binaural Fusion”, “Binaural Directionality”, etc. is intended to indicate support of binaural processes via bilateral processing in the two hearing aids. For cooperative bilateral processing that is not specifically directed to support of binaural hearing processes, we use the term “Synchronized”.