As legend has it, the round table concept dates back to the days of King Arthur. Arthur's table was round to avoid quarrels over precedence. It was there that the knights met to tell of their deeds, engage in merriment, and to plan new adventures. Back in 2002 we had a round table adventure with a touch of merriment here at The Hearing Journal. At that time, we gathered together a group of audiologists for a candid discussion of the features of digital signal processing; maybe you remember reading what they had to say.
Seven years have passed and the knights are back from their travels and adventures. No, I'm not talking about Sir Gawain, Sir Lancelot, or Sir Galahad, but rather our five knights of audiology, PhDs all: Ruth Bentler, University of Iowa; Catherine Palmer, University of Pittsburgh; Todd Ricketts, Vanderbilt University; Robert Sweetow, University of California-San Francisco; and Michael Valente, Washington University in St. Louis. They tell me that while on their travels they observed that one of the hottest topics in the world of hearing aids today is open-canal fittings, so that will be tonight's dinner-time discussion.
The lights have been dimmed, we're at our assigned seats, our goblets have been filled, and we're ready to proceed. I hope you enjoy reading the transcript of our discussion.
A FEW GROUND RULES
Mueller: Okay, knights, settle down. It's time to go to work. I know it's been seven years, but tell your stories later. I'm going to be tossing out a few questions, and let me warn you, your answers just might show up in print. The original Knights of the Round Table had several rules, such as “Seek after wonders.” You all don't seem to have any problem with that, but our round table has its own set of rules, so listen up:
- We're talking about “open-canal” fittings, and I'm going to refer to these products as OCs for short. I'm referring to fittings where the ear canal is open enough that the REOG is not much reduced from the REUG. And, in my book, an OC is an OC is an OC, whether the receiver is in the hearing aid itself or placed in the ear canal—but we'll get to that later.
- What an OC is not is a “CC.” We'll leave that moniker for the grandfather of audiology, Dr. Bunch. By “CC,” I mean “closed canal.” We all know you can take a mini-BTE with a slim tube, or slim wire in a slim tube, and then use some form of a closed or mostly closed earmold. That's another type of fitting, and not what we're talking about today.
- I know you all probably have favorite products, but try to be generic in your comments about features and fittings when it comes to naming names. You will be bleeped.
- There are some well-documented advantages of today's OC fittings, such as the reduction or elimination of the occlusion effect, improved sound quality, and positive cosmetic ratings. We're not going to talk about these known benefits, but rather focus on some issues that are a bit more controversial.
- The final rule? Be nice!
RIC & RITA
Mueller: Let's talk a little about the receiver location of these OC products. As you all know, the receiver-in-canal (RIC) style has become popular in recent years, but there still are many traditional receiver-in-the-aid (RITA) OC models available, and many companies offer both styles.
We've all seen ads suggesting that the RIC style has better sound quality, smoother response, more high-frequency gain, and so on. The annual Hearing Journal/Audiology Online (HJ/AO) surveys also consistently show that the majority of dispensers believe there are advantages to the RIC style (see accompanying sidebar). Is there really evidence showing that this is true?
Palmer: I'm not aware of any evidence from a well-controlled study suggesting that RIC provides superior sound quality, smoother response, or more high-frequency gain than the RITA models. To set up a comparison like this you'd have to make sure that the aids were programmed to provide equivalent outputs in the ear canal, with the canal occluded the same, with only the receiver location being different. In essence, just by setting up the experiment correctly, I think you'd eliminate most if not all differences.
Regarding more high-frequency gain, in my opinion, both RITA and RIC products continue to have inadequate bandwidth—just like all the other hearing aids on the market. None of the hearing aids we've measured have had useful gain/output past 5000 Hz (in most cases, they roll off significantly after 4000 Hz). This is no different from the standard hearing aids we've been using for the past decade. I think what is of concern is that many of these products are being promoted as having a wider bandwidth, and we just aren't seeing this when we make measurements.
Mueller: Mike, you're fitting a lot of RIC products in your clinic, right? Are you finding any significant differences?
Valente: I'd say we probably fit around 40% OCs, both RIC and RITA. Aside from perhaps a smoother frequency response in the higher frequencies, I can't see any major advantage to the RIC style. And there probably needs to be an acoustic advantage to offset the disadvantages created by blockage of the receiver due to cerumen and debris in the ear canal. At times, a day in the clinic just seems like the old CIC-plugged-receiver days revisited, and I've never been a fan of CICs.
Mueller: Our 2009 dispenser's survey seems to agree with you, Mike. The respondents rated the RITA significantly more favorably for both maintenance and repair issues.
Ricketts: I know Catherine said she isn't seeing any real-ear gain difference in the highs for the two different products, but we've seen some advantage for the RIC style as it relates to the presence of gain in the extended high-frequency range (6000 to 9000 Hz or so). The thin tubing of the RITA provides damping for this frequency region, so it appears most manufacturers choose RIC for their extended high-frequency products.
Palmer: Usable gain above 6000 Hz in a real ear for an open fitting? You're kidding, right? What products are you testing?
Ricketts: Well, the @#%@^&^ and the #@*&^!* are two that immediately come to mind.
Mueller: I told you you'd be bleeped! Let me ask about a specific RIC-RITA issue—I've read comments in a couple of articles saying there is less feedback with RIC products, yet I've seen published data to the contrary. What's your take on this?
Bentler: I'm not sure why we would expect to see less feedback. The acoustic feedback pathway is from the sound escaping from the ear canal to the microphone. Whether this acoustic energy is released in the ear canal directly from the receiver or passed through a slim tube should not matter. Receiver size, of course, impacts maximum output, which impacts potential for feedback, but I don't see this as an issue as acoustic feedback usually is present before maximum amplifier/receiver gain is reached.
Sweetow: I don't get it either. Since the most likely source of feedback occurs where the amplified sound enters the ear, there should be absolutely no difference between RIC products and other OCs since they both emit sound within the external meatus, and the feedback path is exactly the same. The only exception might be that the non-RIC would have an additional pathway for feedback located at the junction between the receiver and the tubing, but this is a less likely location.
Ricketts: Well, I guess you all know that I agree with what's being said, as I had a letter to the editor here at the Journal published last year saying exactly that. But to be fair, there are many design considerations and theoretical causes of feedback for both RIC and RITA instruments, ranging from vibrations from the receiver in the RIC style traveling up the thin wire. As Robert mentioned, with the RITA, acoustic seals or the tubing itself could theoretically break down over time.
Mueller: There was an article here in HJ last January showing no difference in gain-before-feedback for paired RIC and RITA models, but you've done some testing in your lab too, right, Todd?
Ricketts: We have. We've examined additional gain before feedback in more than 30 different OC products. All measures were made without any ear canal tip to ensure that the instruments were truly open. We have found large differences across models and manufacturers, but nothing to suggest any systematic difference between RIC and RITA. In fact, because the size of the receiver in the RITA instrument is not limited by ear canal size, we have found the greatest gain in the low frequencies in RITA instruments (albeit in large traditional BTE instruments coupled to the ear using thin tubing). The maximum gain we have measured in the high frequencies has been about 34 dB and this value has been measured in both RIC and RITA instruments.
DO THE MANUFACTURER AND MODEL MATTER?
Mueller: I suspect that there are 50 or more different models of OC products available today if we count only the mini-BTE version, and, of course, you can make most any BTE into an OC fitting. Are there really big differences among models, or are they all pretty much the same?
Palmer: I don't have any data to answer this question, but I will say we've been using several different models clinically and the differences have to do with our preferences for how we control the various features (software differences), lengths of warrantees, and things like that. We conduct probe-mic measures for as many models as we can get our hands on, and really don't see significant differences.
Valente: I'd say that in general, there are no significant differences among manufacturers. In fact, you could probably expand that answer to most all models from all manufacturers, regardless of style.
Sweetow: Catherine, Mike, I don't know about that. I believe there are significant differences among OC models, just as there are differences among various models of any other style. For example, certain models clearly have superior high-frequency responses and feedback-suppression characteristics. Given the critical importance of these features for the population who should be fitted with OC aids, I think it is safe to say that there really are distinctions.
Mueller: That's two no's and one yes. What do the rest of you think?
Bentler: If you're talking about feature differences across manufacturers, I'm a “yes,” since I am here to tell you that all directional-microphone, DNR, and feedback-cancellation schemes are not created equal(ly).
Sweetow: I had one more point to make. I know you're probably asking about differences in signal processing, but I want to add that a difference that can have a vital impact on the overall outcome of the fitting is the physical retention of the device in the ear canal. Regardless of how good the aid is acoustically, if the receiver or coupler constantly migrates laterally, the quality of the signal, as well as comfort and cosmetics, will be altered. I think more attention needs to be paid to the non-acoustical aspects of OC hearing aids. For example, I'm waiting for the coupling of the domes to the receiver or the tubing to be more secure. It seems to me there must be some simple solutions, such as ribbed couplers, for this problem. After all, look how simple, yet effective, replaceable wax guards have become.
Mueller: Good point. Todd, you look as if you'd like to weigh in on this.
Ricketts: You're going to get another yes vote. I think there are clearly big differences both across and within manufacturers, many of them intentional. For example, if you are designing a hearing aid for individuals with normal hearing in the lows, the low-frequency channels can be disabled to conserve battery life and a smaller receiver can be used to improve cosmetics (in the case of RITA) or comfort/openness in a small ear canal (in the case of RIC). Some manufacturers do this, others do not.
And, in agreement with Ruth, our comparative testing also has shown that there are significant differences in the effectiveness of features, such as directional microphones. Because of these differences, I am a big advocate of evaluating OC instruments clinically, although this really only needs to be done once for each specific model.
AND THE FITTING RANGE IS?
Mueller: Our earlier discussion of feedback directly leads to our next topic: What is a reasonable fitting range for OC products? The 2009 HJ/AO survey showed that a quarter of respondents are fitting more than 70% of their patients with OC products. And yes, we emphasized in the question that we were only referring to truly open fittings. That seems a little high to me. I also typically see published fitting ranges going down to a hearing loss of 80 dB or so. Are you all okay with this?
Sweetow: Absolutely not. If our goal as professionals is to provide adequate audibility, we shouldn't compromise high-frequency gain simply because the patient demands better cosmetics or less occlusion.
Palmer: If your goal is audibility for soft, or even moderate sounds, then I think an 80-dB-HL hearing loss is out of the range of these products (if you are going to actually keep the ear canal open).
Bentler: I agree, but I do recall that Dianne Van Tasell presented some data at the Auditory Society Meeting a couple years ago showing that the fitting range (based on NAL-NL1 targets) was actually quite large—larger than one might expect. Since some of the canal resonance is maintained, the output can be expected to be somewhat higher in the higher frequencies. Of course, this needs to be confirmed at the time of the fitting with probe-mic measures. But if the aid is capable of providing even 30 dB of real-ear gain at 2000 to 4000 Hz, which we've seen with some instruments, that would be an appropriate fit for losses up to 65-70 dB.
Ricketts: I think it's going to depend on what model you select, as certainly not all OC instruments have the same gain before feedback possible in the high frequencies. And, as I mentioned earlier, there are certainly differences in whether low-frequency gain is possible. The maximum REIG before feedback that we've measured is about 30 dB at 500 Hz and about 34 dB at 2000 Hz, so it seems clear that fitting hearing losses up to 65-75 dB HL may be appropriate using some instruments. However, more typical OC instruments, with considerably less REIG, would be appropriate only for mild low-frequency hearing loss and high-frequency thresholds of no more than 60 dB HL or so.
Mueller: That's the second time tonight you've mentioned gain of 34 dB at 2000 Hz. For a truly open fitting, that sounds borderline unbelievable to me. Was that for people who were actually out using the aids in the real world, or research subjects strapped to a chair with a head brace in your lab?
Ricketts: Actually, Gus, those are real numbers on real patients, at least sort of. We have the patients walk around and talk, we talk to them, play music and other sounds, etc. when we evaluate maximum gain before feedback with feedback suppression active and inactive. Importantly, this is not based on cases where the patient is wearing it out long term, so I don't know if the lack of feedback would remain over days or weeks.
I should point out that these numbers are not inconsistent with those reported elsewhere. A fully open micro-BTE without feedback suppression will have a maximum stable gain near 18 dB or so. To get to 34 dB we need around 16-dB of additional stable gain before feedback (AGBF). We have not measured the 18-20 dB+ AGBF values reported by some manufacturers, but we have seen 16 dB.
Mueller: Okay, just checking. How do you determine fitting range in your clinic, Mike?
Valente: I tend to be conservative and look at the manufacturer's upper fitting range and reduce it by about 20%. I take this viewpoint because I believe these fitting ranges are a bit optimistic. Also, if I fit to this upper range, then it doesn't allow me any “wiggle room” for using the aid as effectively, or if my patient's hearing should change in the years ahead. And, as Ruth said, what we really want to pay attention to are our probe-mic findings, not a published chart.
Mueller: Let's go to the other end of the fitting range. What about fitting someone with a pair of OCs who has normal hearing through 2000 Hz?
Palmer: I think this works if there is a mild to moderate hearing loss at 3000 Hz and beyond. Despite what Todd says, the reality is that the bandwidth of these devices is going out only to 4000 to 5000 Hz, but, this frequency range can be very helpful in terms of understanding speech. I've found that these are people who come in and say they often feel like cupping their hand behind their ear to hear. They also tend to be people who have high communication demands where hearing is essential (lawyers, judges, parents with teenagers, etc.).
Bentler: Most of our consumers of these products are adults. If we can confirm through probe-mic verification that appropriate gain and output are present, and they confirm the benefit, why not? One of my old professors fits that profile perfectly, and he could be a poster child(?) for OC fittings!
Valente: I have several patients whose hearing in both ears is normal through 2000 Hz and who have mild to moderate-severe hearing loss at 3000-8000 Hz. They are all very satisfied with their hearing aids. These patients typically are communicatively active and public interaction is critical to their quality of life or professional growth.
Sweetow: That's exactly right, Mike. I think the need for amplification should be based on the communication needs of the patient and not simply on the audiometric pattern. If a patient is experiencing difficulty hearing in certain situations for which OC hearing aids might afford better focus or confidence, these devices are appropriate. An example of such a patient is one who has “obscure auditory dysfunction.” Another category of patients for whom OC aids are appropriate even with normal hearing through 2000 Hz are those suffering from tinnitus.
PRESCRIPTION AND VERIFICATION
Mueller: When talking about fitting ranges, at least the upper end, we indirectly were talking about prescriptive fitting approaches. Some people believe that OC fittings require a different prescriptive method from what we typically use for more closed fittings. What are your thoughts on this?
Palmer: You all know what I think about this because I practically went crazy at the Auditory Society Meeting a couple of years ago when people started saying this.
Mueller: The fact that you were sitting in the front row and waving your arms did get everyone's attention!
Palmer: True, but why in the world would the SPL needed at the eardrum of a particular individual to match prescriptive targets (or achieve audibility) be any different because of the delivery system (ITE, CIC, BTE, open-BTE, acoustic trumpet, etc.)?
Bentler: Some of you might recall that a couple years ago we published an article in this Journal showing that, on average, the manufacturer's default for an OC fitting was about 10-15 dB below the NAL-NL1 target for a 60-dB-HL hearing loss in the high frequencies. This was from four separate manufacturers, so it appears that there are some people who think that different prescriptive methods are needed.
Valente: I have to partially take the blame for this one. While I was chairing the recent AAA Task Force to provide a guideline for fitting hearing aids to adults, the group placed into the guideline a statement saying something along the lines that current prescriptive formulas may need to be adjusted for open fits. That statement should never have appeared. I'd say, clinicians should use their favorite prescriptive formula to fit OCs as they do with any other hearing aid style.
Mueller: Wow. A truly heart-wrenching confession from Dr. Valente. We'll get you signed up for a 12-step program when we finish. But first, Todd, I remember that you've conducted some research on this topic, although I haven't seen it published.
Ricketts: You're right, Gus, it isn't published yet, and I'll spare you the heart-wrenching confession that explains why! It goes something like this: Pilot data that I collected with Earl Johnson suggested that traditional prescriptive procedures, such as NAL-NL1, may be a reasonable starting place with OC instruments, just as with traditional instruments, especially with regards to high-frequency targets. That is, we found for both intelligibility measures and speech quality ratings, a slightly modified version of the NAL-NL1 was equal to or better than other prescriptions that altered gain and frequency response. I should point out, however, that our data, as well as those presented by Gitte Keidser at at the 2008 IHCON, suggested that a few dB (4-6 dB) less gain than traditionally prescribed in the low frequencies may also be acceptable, or even preferred.
Sweetow: I agree with all of you, but I believe there are certain patients who are excellent candidates for OC hearing aids whose needs differ from the traditional hearing aid candidate, and maybe you have to look beyond the traditional prescriptive method when you are fitting them.
Ricketts: I was just getting to a similar point. If the patient is under-fitted but is still able to achieve some noticeable benefit, then I'd say fitting an OC instrument is probably okay if the alternative is outright rejection of hearing aids.
Mueller: That takes us to verification. I guess if you use the old “How does it sound?” approach it doesn't matter much if the ear canal is open or closed. But what about the people using probe-mic verification? There's some minor tweaking of the traditional procedures needed, right?
Palmer: Yes there is, and I'd like to say that one of the best sources for clinicians that deals with this topic, and others related to OC fittings, is the HJ article you and Todd wrote a couple of years ago—good information and still accurate.
Mueller: Thanks, Catherine. You mean someone actually read that? I know it's sort of old news, but it might be good to briefly mention the different equalization procedure that needs to be used for OC fittings. Mike, you want to jump in here?
Valente: Sure. I only regret that most people reading this won't care, since they don't use real-ear measures! What Gus is referring to is that it is possible that the output from the aided signal can pass through the wide vent in the ear canal, and then be picked up by the reference microphone, and in fact be greater than the output from the loudspeaker. This more intense signal would then be used to reduce the level of the input signal to the hearing aid from the probe-mic system, which in turn would give you an erroneous aided output.
To overcome these potential problems, I'd suggest leveling your real-ear system as you currently do, with the reference microphone on. However, when completing aided measures for an OC instrument, it's then important to turn off the reference microphone. If you don't, it's possible that your measured high-frequency gain will underestimate the “true” high-frequency gain (i.e., your measured high-frequency response will fall markedly from target).
Ricketts: To continue with the point that Mike is making, if you don't know that this is an invalid output, you will then increase gain to try to match your fitting target and end up with overamplification for the region where the mistake is being made. The magnitude of overamplification will depend on the peak gain of the hearing aid, which in turn will be limited by the effectiveness of the hearing aid's feedback-suppression system. Specifically, the overamplification error can range from 4-5 dB when peak REIG is around 20 dB and to more than 15 dB when peak REIG is more than 30.
Mueller: The main message for the clinician, then, is to use stored equalization rather than concurrent equalization, an option available with all modern probe-mic equipment.
Ricketts: Right, but I do want to add that it is critical when verifying OC instruments using stored equalization that the patient remain stationary during calibration of the reference microphone and throughout the remainder of the testing period. If the patient moves, the reference microphone will need to be recalibrated before continuing with testing.
REAL-WORLD BENEFIT OF SPECIAL FEATURES
Mueller: Directional-microphone technology is pretty much standard in all products these days. What are your thoughts about the real-world benefit of this feature with OC products?
Bentler: There are published data relative to directional-microphone benefit with an open fitting. As you say, they tend to be pretty much standard, and it seems as though they can do little harm, so I say why not?
Sweetow: Right. Some people have the notion that directional benefit is only for the lows, but there is plenty of research supporting the concept that this feature is effective in the high frequencies as well.
Ricketts: In my laboratory we have shown that average directivity, as quantified by the directivity index (DI), is a fairly good predictor of the directional benefit average patients receive in environments where the speech is in front and noise surrounds. Related to what Robert was saying, since gain is needed for directivity and low-frequency DI is reduced by venting, it is not surprising the average DI in open instruments is approximately half that measured in a well-performing closed instrument. We therefore might expect about half the directional benefit in an open instrument compared to the best performing closed instruments. And Mike, didn't you just report that that was good enough to result in patient benefit?
Valente: I assume you're referring to the recent IJA article I wrote with Karen Mispagel. Yes, we found significant benefit for the directional mode for both testing in the clinic and the field trial. I'd like to point out that sometimes we forget that even though the average DI for OCs may be only around 2.0 dB, the DI for the alternative, an omnidirectional fitting, is not 0 dB, but a negative number; hence, the benefit over omnidirectional is greater than 2.0 dB.
In our study, the subjects did no better in the OC omni-directional mode than they performed unaided! I should add that we were careful to assure that these individuals had appropriate high-frequency gain. If you send people out the door with little gain in the highs, as Ruth mentioned earlier, then of what benefit could a directional microphone be? Just another reason why you need to verify real-ear gain for these instruments, but I guess we've all said that at least once already.
IT'S CLOSING TIME
Mueller: Okay folks, our time is winding down. But before we wrap things up, let's talk a bit about post-fitting counseling and follow-up visits. Is that any different for patients fitted with OC products?
Sweetow: I think OC candidates often erroneously think either that sounds should be louder or that sounds should be perfectly natural. I frequently use the line, “If it sounds right, it's wrong!” I advise them that they should expect to hear sounds differently and that they need to experience the difference for at least a week before deciding whether I need to alter the amplification characteristics.
Palmer: It isn't really different in terms of the things you need to cover, but some of the solutions may be different. Because the ear is open, you potentially have several options for using a cell phone or landline phone (right to the open ear, through a telecoil in the mini-BTE), and you have different options for coupling with other stuff people might like to put in their ears (earbuds, stethoscopes, etc.).
Mueller: Well, they've turned the lights up, we missed last call on goblet refills, so I guess it's time we pack up. Any closing comments?
Palmer: Well, since nobody else is talking, I do have a final point. Like everyone, we are fitting a lot of people with OCs. But I want to point out that this increase is not because we are trying to put OCs on everyone who walks in the door. It's because we are seeing many more people with mild-to-moderate high-frequency hearing loss. These people are coming in much sooner than the previous generation, so we get to start working with them when their hearing loss is not as bad.
This has been a real treat in the clinic and it is terrific that we have an excellent array of products that meet their needs.
Mueller: It's always nice to end on a positive note. Good night, all!
RIC VERSUS RITA—THE SURVEY SAYS...
There is a wide variety of open-canal (OC) products, with many different types of styles and features available. One distinguishing feature of these instruments is whether the receiver is in the hearing aid (RITA) or in the ear canal (RIC). Clearly, removing the receiver from the hearing aid frees up some space, and allows for more creative style choices. Everyone agrees with this. What everyone does not agree on, however, is whether or not there is any acoustic advantage of RIC versus RITA. We thought it might be interesting to see what the average dispenser believes, so we included some RIC versus RITA questions in our 2009 annual Hearing Journal/Audiology Online survey.
Various acoustic and fitting issues related to these two products were listed on our survey, and respondents were asked to select the style they believed would have superior performance, or if they believed they would perform equally to select “no difference.” Survey results were obtained from 425 people who dispense hearing aids in their practice. Of these, 277 (65%) were audiologists and 148 (35%) were hearing instrument specialists (HIS). Because several different types of earmold options are available for both RIC and RITA fittings, including a completely closed ear canal, our survey instructions emphasized that the questions applied only to when these products were fitted with open-canal configuration.
The overall findings from this survey are shown in Figure 1. We did not include the “no difference” responses, which averaged 40% of all responses. Rather, we are displaying only the RIC and RITA preferences, as that was our main interest (100% minus [%RIC + %RITA] = % “no difference”). As shown, for most acoustic issues, our respondents had a definite preference for the RIC style. Areas where this was most pronounced were high-frequency gain (54% versus 16%), reduced feedback (48% versus 19%), and sound quality (44% versus 13%).
Given that with an open fitting we would expect to obtain the same ear canal SPL with either RIC or RITA, and since ear canal SPL drives speech intelligibility, it's interesting and somewhat puzzling to observe that 35% of the respondents believe that superior speech intelligibility will be achieved with the RIC style (compared to only 11% favoring RITA; 54% selected “no difference”).
Recall that our survey was about 2/3 audiologists and 1/3 HIS. We thought it would be interesting to see if this preference for the RIC style was statistically the same for both groups. It was for some categories, but not for others. In general, the HIS group were stronger advocates for the RIC, whereas audiologists had significantly more ratings in the “no difference” category; the preference ratings for RITA for all categories were very similar for both groups. The category where the most notable difference was seen was speech intelligibility, where 50% of HIS favored the RIC versus only 26% of audiologists gave this response. Other acoustic factors where large inter-group differences in favor of RIC were seen were sound quality (57% of HIS versus 35% of audiologists) and smoothness of response (51% versus 32%).
Within the audiology group, we also examined preferences based on other demographic factors. There was no significant RIC versus RITA preference interaction related to highest degree earned, work setting, or years of experience. There was, however, a significant gender difference for four of the factors: maximum gain, reduced feedback, repair, and maintenance. In all cases, males were more likely than females to favor RIC over RITA.
In general, our findings suggest that the RITA is preferred for maintenance and repair, but when a preference exists for acoustic parameters, it's always in favor of the RIC style. Is this preference based on research findings, clinical experience, or effective marketing? See what our panel of experts has to say on this topic in the accompanying Round Table Discussion.