Listening with a “Third” Ear: FM Systems
By Mark Ross
May, 2004
No one doubts that in the last ten years hearing aids have become smaller and “smarter.” Many are now capable of processing speech and noise in ways that we could hardly even dream of in years past. Features like multiple bands, wide dynamic range compression, automatic feedback suppression systems, and directional microphones are now routine. Still, in spite of these and other developments, none are as capable of increasing the speech to noise ratio (the intensity level of the speech relative to the noise) as much as a close-talking microphone (where a microphone placed just a few inches from a talker’s mouth). And of all the factors that affect speech perception capabilities, none are as important as the signal to noise (S/N) ratio.
It’s obvious that if a speech signal cannot be heard over the background noise, it will not be understood. While perhaps not so obvious, it’s also clear that the more a speech signal surpasses the noisy background (up to about 20 or 30 dB for a hard of hearing person), the better someone will understand a verbal message. No hearing aid feature yet developed is able to strip only the noise (which could be other persons’ speech) at times when speech and noise arrive simultaneously at the microphone. Directional microphones are one hearing aid feature that can and do improve the S/N, but they accomplish this by suppressing sounds from any other direction than directly in front. Obviously, they are a highly desirable feature included in many modern hearing aids. To take the best advantage of their capabilities, however, people wearing directional microphone hearing aids do have to consciously position themselves favorably in respect to the location of the speech and noise (desired signal in front, noise to the rear if possible). The problem with directional microphones, no matter how advanced they may be, is that they remain fixed to the head. I’m not being facetious. It is physically impossible for hearing aid users to locate themselves in an optimum location for receiving a desired signal. Hearing aid users can hardly place an ear six inches from the mouth of a lecturer, a tour guide, a passenger in a vehicle when they are driving a car, or one’s conversational partner at a reception or a restaurant!
It is in these type of situations that FM systems, and at the present time only FM systems, can significantly help a hard of hearing person hear better. An FM listening system is basically an FM (frequency modulated) radio. A microphone picks up the desired signal, and a transmitter “broadcasts” the signal to an FM receiver (the “radio”) worn by the recipient. Unlike hearing aids, the microphone of the FM system can be placed close to the source of a sound, no matter where it is. It is this simple fact, i.e. the “portability” and flexibility inherent in personal FM systems, that is the heart of their potential effectiveness.
Initially, FM systems were designed specifically for use by hearing-impaired children in schools. The teacher wore a large lavaliere microphone-transmitter around her neck (later replaced by a lapel microphone and a belt transmitter). The original FM receivers, worn on the body, directed sound signals to the children’s ears via miniature earphones. Later, various ways of coupling their own hearing aids to FM receivers were devised. These systems had a profound impact on the educational placement and performance of children with hearing loss. They helped to overcome the deleterious effects of poor classroom acoustics, then found in most classrooms in schools throughout the country. For the first time, ever, children could be assured of a highly positive signal to noise ratio while permitting both teachers and students full physical mobility throughout the classroom. In my judgment, it was the availability of FM systems that made mainstream placement of children with hearing loss a feasible educational placement alternative.
Few adults, however, chose to use these original FM systems. They were cosmetically unacceptable to many people with hearing loss and just a bit too unwieldy for everyday use. Adults who did employ them, however, reported that these systems provided a significant boost in their ability to receive spoken messages in a number of situations (e.g. lectures of various kinds, tours, noisy restaurants). Still, in spite of their proven ability to improve speech perception in many listening conditions, only a relatively few adults were sufficiently motivated (and secure in themselves) to use them. Indeed, many hearing-impaired adults were not even informed of their existence, since most hearing aid dispensers simply “assumed” that their clients would not be interested in such a cosmetically unappealing device and never raised the possibility with them.
This is where the new generation of personal FM systems comes in. These systems are smaller and much more convenient to use than the older ones. The microphone/transmitters are about the length of an eyeglass case, but narrower. They can be hand-held in situations where the source of sound is relatively close or physically placed next to more distant sound sources. They represent, in fact, an easily portable, “third” ear. The signals broadcast by the transmitter are detected by an FM “receiver” boot plugged into the bottom of behind-the-ear (BTE) hearing aids. Many of the newer generation of BTE hearing aids, not just from the manufacturer of a specific FM system, will accept such a boot. One company (AVR Sonovation) makes BTE hearing aids with internal FM receivers. Thus clients cannot only be informed of the potential advantages of a personal FM system, but because trials would be so easy to arrange, an actual trial should be easy enough to provide for those people who are potentially good candidates.
Let us consider some of the types of situations in which having such a “third” ear can be employed. I shall review here mainly those that I myself experienced and comment on a few other potential applications, particularly in various kinds of employment situations.
1. One persistent problem that people with hearing loss complain of is their difficulty hearing their companion in a noisy restaurant. A personal FM system is made to order for this type of situation, particularly if only one other person is involved. The dining partner simply places the transmitter close to him or her, either on the table, around the neck (a cord comes with the microphone) or in a pocket. And that is all there is to it. My wife often reminds me to bring my FM system when we go to a restaurant. It makes life not only easier for me, but for her as well. Without an FM, talking to me in a noisy restaurant is a bit of a strain. She finds herself leaning over the table, struggling to make sure I understand. With the FM microphone, she can sit back and relax (and then she says that she has more difficulty understanding me than I do her!).
2. The situation is not quite so positive when other another couple is present. In these situations, the FM microphone has to be placed in the most strategic location, as close to everybody as possible. I usually place the microphone between the other two people on the other side of the table. To hear the person next to me, I set the hearing aid to the FM/M position, where both the FM system and the hearing microphone are picking up sounds. Far from perfect, but better than trying to hear the three other people with my hearing aids alone under those conditions. To be realistic, dinner with a large group in a noisy restaurant or at a banquet is often an impossible situation. In this situation, one can communicate effectively only with the people immediately to one side or the other. Probably the best bet in this circumstance is to employ directional microphone hearing aids (being sure to locate the band or other major sources of source to one’s rear). In other words, taking advantage of a personal FM system does not mean that we should ignore the potential benefits of directional microphone hearing aids.
3. People with hearing loss watch the lips of a speaker for a good reason: it improves their understanding of speech. However, when driving a car it is not a good idea (to put it mildly) for the driver to watch the passenger rather than the road when engaged in conversation. At this time safety is more important than communication. But we can have it both ways. By talking into the FM microphone, a passenger can talk to a hard of hearing driver without the driver taking his or her attention away from the road. I know that whenever my wife and I take a long drive in our car, I always bring my FM system. I often bring the FM system whenever we drive with another couple. If we’re in the back seat, I can hold the microphone between the two front seats when talking to the other couple. If the other couple is in the rear, then my wife either places the microphone behind me or we hand the microphone to the people in the rear seat. Again, not a perfect solution, but a lot better than depending on hearing aids alone.
4. A hand-held FM microphone is the best way that I know of for a hard of hearing person to function tolerably well in a noisy group situation, such as in a reception. At such events, people are standing, talking, and milling around. All one has to do is place the microphone as close to the lips of one’s conversational partner as feasible. This can be a bit awkward at first for both parties. Many hearing aid users feel that this is a too public display of their handicap (and, yes, a hearing loss is a handicap no matter how one slices it or defines it). Some conversational partners may react negatively to having a microphone placed close to their mouths (while others preen a bit while looking for the hidden camera!). It does take a modicum of assertiveness for a hard of hearing to use an FM microphone in this manner, but it soon becomes the most natural thing in the world for both parties. It does illustrate the important fact that communication is truly a two-way street. It also illustrates perhaps the most crucial point of all insofar as reducing the problems caused by a hearing loss, and that is that the person involved bears the greatest responsibility.
5. Most people in our society enjoy watching TV at home. There, one can use any number of permanent TV listening systems to enhance comprehension (Infrared or FM transmitters or a floor loop system). This is not possible when traveling and one is staying at a hotel. In these places all the hard of hearing person has to do is locate the FM microphone and transmitter next to the TV speaker. The close distance between the TV and the FM microphone ensures a loud and distortion-free signal transmitted to a listener. I know that when I compare this condition to what I would understand with my hearing aids alone, there is a clear-cut advantage to the FM condition. When traveling with my wife, I can watch (and understand) TV without disturbing her while she is reading. Often she tells me that she can hardly hear the TV at all at times that I’m picking up an excellent signal.
6. There are other uses in having a “third”, remote ear available. I’ve used FM systems in small meetings (placing the microphone on a table), walking down the street in a noisy city, at lectures, and on various tours. In respect to this latter use, the FM system makes it unnecessary for a hard of hearing person to elbow other people aside while trying to get close to tour guide in order to hear. All that is necessary is that the tour guide wears the FM microphone. I know of workers in various noisy factories who use an FM system to talk to their supervisor or co-workers, interviewers who place the FM microphone close to an interviewee, and hard of hearing teachers who require their students to talk into their “third” ear. I have velcroed the FM microphone to the loudspeaker of PA systems in places that did not supply an installed assistive listening system. In other words, an FM system can be used in any situation in which the desired source of sound is some distance from the listener. All it takes it some ingenuity and a fair amount of assertiveness.
As these examples amply illustrate, the listening advantages for hard of hearing people of a personal FM system are many and manifest. The combination of boosting the S/N to a degree not yet possible with any other technology, plus the ability to physically place the microphone close to a sound source, can make these systems extremely beneficial for a user. So why aren’t more hard of hearing people using them? Why do we so rarely see people using such a system?
Part of the reason has to be the cost/benefit ratio as perceived by the user. Even when there is proven subjective and objective benefit, adults who have tried personal FM systems have elected not to use them when it entailed purchasing them. At the International FM conference in Chicago (November 11-12th 2003), there were two papers that evaluated the performance of people with personal FM systems. In both studies, the acoustic advantages were apparent to both the researchers and the clients. One group, those who were able to obtain the FM systems free of charge from the Veterans Administration, opted to keep the systems. They did report that they would be willing to pay between one and two thousand dollars extra for the unit, considering the acoustic benefits it afforded them. Still, they didn’t actually have to lay the money out.
In the other study, conducted at two separate sites, the subjects were not veterans. Although there was ample evidence that the FM systems substantially improved speech comprehension in noise, and the subjects had ample opportunity to try the systems at home, only four people elected to purchase the FM system they had tried, even with a significant price reduction. From my perspective, this is a very disappointing report. But it is a reality and one that does have to be faced. However for the subjects in this study it was a package deal. They were also required to purchase the expensive hearing aids that were part of the experiment (high-end digital hearing aids). So we don’t really know what their response might have been if they had been offered only the FM system. Perhaps if only FM systems were involved, and not hearing aids as well, their decision would be different. But at this time, we simply do not know.
So what’s the solution? How can we get more people to take advantage of devices that can offer significant help to the average hard of hearing person in many situations? The listening problems most hard of hearing people face is not as dire as it is for people who obtain cochlear implants; these people have reached a point where their hearing problems have become intolerable. On the contrary, most other hearing-impaired people “get along” one way or another. Those with milder losses may feel that they have little difficulty in most situations and that the cost of an additional device is not worthwhile for them. For those with more severe hearing losses, however, while they may “get along,” they manage this through a combination of pure denial, lower expectations, restrictions in their daily social and cultural routines, and an acceptance of greater tensions within themselves, their family and their social circles. Often, they are simply resigned to their situation, not really understanding or appreciating that some amelioration of their difficulties lies within their grasp
The potential users of personal FM systems are those adults who already wear hearing aids. They know the benefits they experience with their personal hearing aids. But they, and indeed anybody wearing hearing aids, also know the many times and many situations in which a hearing aid while necessary, is in itself insufficient. These are the types of situations that lend themselves to discussions with one’s hearing aid dispenser to determine if an FM system can help improve communication access. Often, the kind of problems that are described so obviously be helped with a personal FM system that a recommendation for purchase can immediately be made. At other times, when there is doubt, a supervised trial program can be arranged to determine if the perceived benefits are worth the cost. But unless hearing aid dispensers routinely include the evaluation and need for a possible “third” ear in their clinical practice, nothing will be done. Most people with hearing loss never heard of personal FM systems and know nothing about them. It is the responsibility of hearing aid dispensers to make this information available to all of their clients (as well as information on the full range of other hearing assistive technologies available).
It is my personal belief that personal FM systems would be widely accepted and used if their cost were drastically reduced. Adding the cost of two FM boots and an FM microphone/transmitter to the cost of two modern hearing aids is just too big a chunk for most people to swallow easily. Unfortunately, this is rather difficult to do unless economies of scale can be applied. But this presents a bit of a conundrum: More people would have to purchase these systems in order for their cost to be reduced, but people are reluctant to purchase them because the cost is too high. But I also believe that more people would obtain these systems even now if they were significantly improved in size and performance. Ideally, (and in my dreams), they should be no bigger than a ball-point pen, and be able to hone in on a talker five or six feet away (like across a banquet table), while markedly rejecting sounds arriving off the focus point (as narrow as possible). It would also help if they performed multiple tasks, like serving as a remote control for personal hearing aids (which is what the new Phonak SmartLink is designed to do).
If any hard of hearing person needs to be convinced of the potential value of personal FM systems all they have to do is attend a convention of the Self-Help for Hard of Hearing People, Inc. (SHHH) convention. Personal FM systems are a ubiquitous presence, used by people who know how valuable they are. Any one of these people would be happy to testify to the value these systems offer them in their daily lives.
