Hearing Aids, Real-Ear Measures, FM Technology, and More: An Interview with Michael Valente, PhD

Hearing Aids, Real-Ear Measures, FM Technology, and More: An Interview with Michael Valente, PhD

December 18, 2008 Interviews

Michael Valente, PhD, co-editor of Audiology: Diagnosis, Treatment, and Practice Management, discusses the details of his recent book with Douglas L. Beck, AuD, Web content editor.

Academy: Hi, Michael. It’s always a pleasure to speak with you.

Valente: Hi, Doug, great to speak with you, too.

Academy: Michael, I wanted to spend a little time discussing the “Trilogy” book series, and then if we have time, perhaps a few hearing aid questions, too?

Valente: That would be fine, Doug. Let’s do it.

Academy: Okay. Based on my knowledge of authors and co-authors, editors and co-editors, in general, when people write extensive works together, they usually swear off writing together! But you guys have created the second edition of the Trilogy, and that’s an amazing accomplishment. What inspired you?

Valente: Well honestly, you’re right. When we finished the first Trilogy, we all said “never again.” It was so many evenings and weekends, and so much work. But then at the AudiologyNOW! meeting in Salt Lake City, the three of us got together with the folks from Thieme and they brought up the issue of doing a second edition. Initially we said, “no thanks,” but then the more we thought about it, we realized we had so much fun working together, and we all learned so much that we decided to do it again.

Academy: That’s great, Michael. What a nice tribute to the three of you! Okay then, let’s move on to some of the issues in the “Treatment” book. Let’s start with hearing aid directionality and adult fittings. Directionality is the only hearing aid feature we can offer that improves the signal-to-noise ratio (SNR). What are your thoughts on directionality?

Valente: Directionality is absolutely a wonderful thing and probably is the most important feature from our perspective with regard to amplification. From my personal perspective, another very important consideration regarding directionality is that with open fittings, directionality is also important. In fact, if you dispense an open fit without directionality, it’s a dis-service to the patient. There have been a few articles that have shown when people wear open fits with omni mics, the performance in noise is going to be poorer than when they’re unaided. So bottom line, we’re very strong advocates for directional fits. The only other thing I would add is that of you can add FM technology to the hearing aid, you can improve the SNR by 18 to 20 dB and provide the wearer with performance better than that experienced by people with normal hearing.

Academy: I agree, Michael. Very well said…and what about binaural fitted FM?

Valente: Well, if you add a second FM receiver on the second ear of a binaural fit, you’ll improve the SNR by another 3 dB, and that’s about as good as it gets, particularly in noisy areas, restaurants, shopping malls, and school settings.

Academy: With regard to the directivity index, I recall that a 1 dB improvement in SNR equates to about 15 percent with respect to open-set sentences? Is that about right?

Valente: Well, it depends on a few factors, but, yes, if you use HINT sentences, it gives you about a 10 percent improvement. So , in essence, a 1 dB improvement in the audibility index, which is about a 1 dB improvement in the SNR, will give you about 10 percent improvement in noise, while using open set sentences as the primary signal.

Academy: Isn’t the theoretical limit of the directivity index about 5 dB?

Valente: Well, yes, but again, it depends on the specifics. Using a loudspeaker directly from the rear, with ideal conditions, probably a 5 dB to 6 dB advantage can be realized. But if you’re talking about a diffuse listening situation with multiple loudspeakers to the sides, the rear and in front, you’ll likely see a 2 dB to 3 dB improvement.

Academy: Okay, great. Let’s change the topic to noise-reduction circuits. I think one big issue with noise reduction is the name of the circuit. Of course they don’t actually reduce noise, but they do reduce the annoyance, they improve comfort.

Valente: Exactly. Noise reduction does nothing to change the SNR, but they do make it more comfortable to listen in noise. Noise reduction makes sense just about all the time, with perhaps the only exception being in a very, very quiet situation. In that situation, noise reduction may have little to no role play and I’m not sure it would add anything.

Academy: Agreed, but I wonder, would it take anything anyway? And, if not, why not just keep it active for most or all listening situations? Assuming you have a good quality noise-reduction circuit.

Valente: That’s a wonderful question and I’m not sure I know the answer to that. I’ve never read a study where noise reduction damaged the speech signal, so it’s probably okay.

Academy: Okay, let’s change subjects again if you don’t mind…what about feedback management through 180 degree phase shifts? Seems to me that is an enormous step forward and very important, as we can finally program in the high frequency gain we need without mandatory high frequency attenuation, and without notching the response?

Valente: Yes, absolutely. Feedback management has come full circle and the advances here make open fits far more viable than ever before, because, as you say, you can finally program and achieve the gain you need.

Academy: What about price—does it matter?

Valente: No doubt at all. Price matters a great deal. We actually break down the technologies we dispense into six categories. Level one is the premium product with all the features and level six is the economy model. I think for a clinic to be viable, you need to offer different levels of financial commitment, and this is even more true today when the economy is struggling.

Academy: What about cosmetics—how important are cosmetics with regard to hearing aids?

Valente: The better they look, the more they appeal to consumers. The mini BTEs with the slim tube and the receiver in the ear models with the wire are attractive solutions and they really offer nice options for most patients, and patient respond positively to these options.

Academy: Michael, what about real-ear measures (REM)? It seems only about 20 to 30 percent of audiologists bother to use real ear. Maybe the equipment is too expensive, or maybe it takes too much time, I don’t know why more audiologists don’t do it, but my question is, “If you could only do one real ear measure, which is the most important REM?”

Valente: Okay, I’ll answer that question, but let me preface it by saying that I don’t know how anyone can dispense without REM, it is so valuable in every fitting. But okay, if I could only have one REM, I would go with real-ear insertion gain (REIG) at 50, 65, and 80 dB input, but then again, you can do the same thing with real-ear aided response (REAR) within the person’s dynamic range using live speech mapping.

Academy: Okay, very good. One specific thing I’d like you to address from your book is a statement in Chapter 6 that says something along the lines of, “if your hearing aid fitting does not improve speech recognition in noise, that the fitting is not acceptable.” Do you agree? And how do you go about it?

Valente: Yes, I think that’s a defensible position and I agree. First, the professional really should strive to improve the patient’s speech in noise performance, because that is such an important problem for so many patients. So you do that through counseling with regard to realistic expectations as to what the hearing aids can and cannot do. Second, directional microphones make a big difference, as we’ve already discussed. Third, it’s important to offer every patient a hearing aid technology (HAT) for specific situations and to overcome specific complaints.

Academy: Michael, what are your thoughts on fitting hearing aids on patients with dead hair cell regions?

Valente: Excellent question. I think we just don’t know enough about this yet to have firm fitting guidelines. It’s hard to know where the demarcation is between benefits and disadvantages, and hard to know the loudness levels, too. Some studies suggest 55 dB and others say 70 dB to 75 dB. We generally fit the patient as best we can, and then if the sound is degraded by adding specific spectral information, we reduce that band or spectral area and we fine tune as needed.

Academy: What are your thoughts on frequency compression or transposition?

Valente: Well, Doug, as you know, there are three or more manufacturers with these technologies available out there right now. From our perspective, with our patients, and from their subjective perspectives, the technology so far, has been essentially unsuccessful with two of the three. We’re interested in trying the third, but at this point we have no experience. So, from my perspective, the jury is still out.

Academy: Lastly, Michael, is hearing aid fitting an art or a science?

Valente: I still think we must have boatloads of scientific knowledge to do our jobs well, and professional knowledge, too—then, we have to combine that with people skills, so I still maintain it’s both art and science.

Academy: Michael, it’s always a pleasure speaking with you. Thanks so much for your time and for sharing your knowledge.

Valente: My pleasure, Doug. Thanks for your interest.

Michael Valente, PhD, is a professor of Clinical Otolaryngology, the director of the Adult Audiology Program at Washington University, St. Louis, MO, and the chair of the American Academy of Audiology’s Publications Committee. He is also the co-editor of Audiology: Diagnosis, Treatment and Practice Management (Second Edition, Thieme ISBN 978-1-58890-542-0).

Douglas L. Beck, AuD, Board Certified in Audiology, is the Web content editor for the American Academy of Audiology.

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