Considerations of CNS Auditory Processing in Hearing Rehabilitation for Older Adults: Addressing Their Listening Environments and Those Who Speak for Them

By Raymond H. Hull, PhD, FASHA, FAAA

The Problem

The role of the audiologist in providing hearing rehabilitation services to older adults with impaired hearing increases as our knowledge of hearing impairment and the needs of adults with impaired hearing likewise expands. However, the complex nature of the aging peripheral and central auditory systems and the equally complex nature of older adults and their communicative requirements can challenge even the most skilled specialist in the hearing rehabilitation process.

Further, the listening environments in which older adults find themselves can make providing services to those with impaired hearing an even greater challenge. In fact, when older adults with hearing impairment describe their most challenging listening situations, the environments in which communication is to take place inevitably become an important part of the discussion, along with the speaking habits of the persons who communication with them.

 

The Need for Environmental Design Modifications for Older Hearing-Impaired Adults

Many public and private listening environments play havoc with the aging peripheral and central auditory systems. As adults grow older, those who at an earlier age may have noted only some difficulty in specific degraded listening environments may now be experiencing frustrating difficulty. Acoustic and visual environmental factors may be interacting to cause the aging adult difficulty in speech understanding, although the reasons may not be evident to the listener.

Older adults may blame the difficulties on the speaker, and, in fact the speaker may be a primary cause of the difficulties. However, part of the problem may lie with the reverberant characteristics of the meeting room, the anechoic environment of their home, the combined effects of both auditory and visual distractions of a social environment, or the interaction of a speaker with less than adequate speaking habits with the environment. All these factors can compound the difficulties in speech understanding that result from an aging peripheral and central auditory processing system. As a result, older adults may avoid places where  they would otherwise like to be, leading to greater isolation than is necessary.

In the end, to provide  their patients with constructive hearing rehabilitative services, audiologists and others who serve older adults with impaired auditory function should become more conversant in the important area of environmental design and speaker characteristics. Services in environmental design are very tangible, and in many instances provide immediate benefit to one’s patients.

 

Problem Listening Environments

Meeting rooms, classrooms, church sanctuaries, church fellowship halls, nursing home all-purpose rooms, auditoriums, bank lobbies, and many other environments in which adults of all ages are required to listen and communicate are generally not conducive to hearing and understanding speech (Tinianvoc, 2009). They may either resemble reverberation chambers (too many almost subliminal echoes) or, on the other hand, anechoic environments (home environments in which sound does not carry well).

It seems that many listening environments are constructed on similar principles. Either square or rectangular in shape, they have hard floors (tile, concrete, marble, or wood); sheetrock, concrete block, or brick walls; “acoustic” tile ceilings that are sound reflective; white boards or black boards in classrooms and some meeting rooms; and uncovered windows, glass-covered pictures, and other sound-reflective surfaces. Furthermore, most church sanctuaries have hard wooden pews, vaulted ceilings, stained glass windows, hard reflective walls, and hard floors (except for perhaps a strip of carpeting down the center aisle), all of which are sound-reflective/reverberant surfaces.

The reflective surfaces described above can result in speech understanding difficulties far greater than would occur in a less reverberant listening environment. Persons with normally functioning auditory systems may not notice those distortions. However, persons with an aging peripheral and central auditory decline may have significant difficulty interpreting what is being said to them, with or without hearing aids.

 

Homes

Typical home environments interact with sound in a manner opposite that found in the reverberant environments of churches and many meeting rooms. Homes are designed for comfort, and are generally furnished so that there are few, if any, reverberant characteristics. They become essentially anechoic chambers. That is, they do not give sound the “life” that it needs to travel well. There may be few, if any, reverberant characteristics that enhance sound transmission.

Many homes are designed, for reas0ns of comfort, to restrict the movement of sound by absorbing it. Soft carpeting, window drapes, soft chairs and sofas, wall paper, and heavily textured ceilings all absorb sound, so a complex acoustic signal such as speech cannot travel far enough to be heard well from any distance or any angle. Further, since speech comprises an extremely complex set of acoustic parameters, it cannot negotiate stairwells (up or down) efficiently, or travel through doorways, move around corners, or through walls without losing important acoustical characteristics. Music is a less complex signal, and so can be carried with at least a fair degree of accuracy in a home environment—perhaps not the words to the song, but the melody will travel fairly well.

 

Redesigning the Listening Environment

It is unnecessary to engage in extensive renovations when working to improve environments for purposes of hearing and listening efficiency. Even modest changes in the listening environment can make a positive difference.

 

Meeting Rooms, Church Sanctuaries and Other Typical Listening Environments

The task here is to reduce the reverberation/echoes to enhance the transmission and quality of distortion-free speech so that it is more easily heard and understood (Anthony, 2006). The frustrating aspect of a reverberative listening environment is that the room may actually carry the speech signal so well that the individual experiences little difficulty “hearing.” It seems to the listener that she or he is hearing fairly well, or at least that the sound is loud enough. However, the reverberation results in frustrating difficulties in understanding what is being said.

The real task is to reduce reverberation without removing the “life” of the room, which supports the natural transmission of speech from the mouth of the speaker to the ears of the listeners (Yoichi, Sato, and Nakajima, 1997). In other words, we must avoid changing the room so that it becomes one without echoes, caused by adding too much absorbency to the room. For example, providing a good listening environment does not always mean adding carpet.

Here are some suggestions to consider. Not all these are required to change the listening environment. Choose one or two, and they may suffice:

1. Since rooms where meetings or classes are held are usually square or rectangular, and thus naturally reverberant, do whatever is necessary to do away with this configuration. You can do so by adding light-weight ceiling-to-floor drapes that are hung by an expandable curtain rod at two opposing corners of the room. If the drapes are positioned far enough away from each corner, the space can be utilized for storing folding chairs and other items, thus adding a small amount of usable storage area. In this manner, the room is no longer square or rectangular, and reverberation will likewise be subdued.
2. Hang light-weight, attractively colored drapes to the sides of windows (not over the windows), the length being two to three inches above and about six to eight inches below the window. Or, if there are no windows, hang decorative light-weight floor-to-ceiling pleated drapes at a few strategic locations along the walls. Colors that blend or complement the existing colors of the room will add to the attractiveness of the environment. This author is partial to cranberry or light burgundy drapes, lightly pleated or gently pushed together on the curtain rod to resemble pleats.
3. If a high ceiling is the problem, try hanging attractive decorative flagging periodically across the ceiling to reduce echoes. This author recommended that strategy for a large meeting room in what is called “The Boat House.” Five-foot by three-foot “flagging” containing pictures related to a nautical theme of boats, water and sky was suspended at various locations across the ceiling. Those were appropriate and attractive for that room, fitting into the nautical theme that the manager had chosen.Note: For items 1-3, it is important not to overdue. Do not turn a reverberant environment into an anechoic chamber. Moderation is important. Some reverberant “life” in the room is important for sound transmission, but just not too much!
4. If there is a noisy pop machine, ice maker or water fountain near a meeting room doorway, make sure it is muffled or quieted as much as possible. If neither option is possible, simply have it moved to another location.
5. If there is an area that is used for food preparation attached to or near the meeting room, use heavy drapes to block off that area to quiet the noise of pots and pans, people talking and so on. If money is available, add a wall with a sliding door to block off that area.
6. Make sure that the PA system is adequate. A poor or unused PA system can be one of the greatest detractors to successful meetings, particularly when there is to be a speaker for the program, or the secretary is to read the minutes of the previous meeting along with the treasurer’s report.

 

Redesigning the Listening Environment for Homes

As stated earlier, many homes are literally anechoic chambers. Speech does not travel well in that type of environment. Sound, particularly a complex set of acoustic signals such as those that comprise speech, is absorbed rather than transmitted to the listener. Speech may not be able to travel far enough to be heard or understood well. People who live in those homes probably did not furnish them on purpose to be without the reverberance necessary to transmit the sounds of speech well. It was perhaps because they did not know about the impact of softness and absorbency on the transmission of speech.

People generally entertain in the living or family room. Typically these rooms are not ideal environments for conversation, particularly if they contain soft overstuffed furniture, carpeting, heavy drapes, or textured wallpaper, textured ceilings, and perhaps some background music added, all making communication more difficult.

Here are some suggestions for a home environment that will enhance the transmission of the acoustical characteristics of speech, and therefore enhance speech understanding:

1. Some suggestions include (a) replacing heavy carpeting with laminated wood in a room that is used as a place for conversation; (b) replacing heavy drapes with attractive window blinds or light weight drapes; or (c) replacing couches and over-stuffed chairs with ones that have greater firmness.
2. Auditory distractions must be reduced. When communication is to take place, turn down (or off) the TV or stereo when conversing with others.
3. Do not attempt to communicate when speaking to another person who is located around the corner, in another room, upstairs, downstairs, or on the other side of an open doorway. The sounds of speech cannot travel well through or around any of those obstacles.

 

Lighting

Careful attention must be given to lightening. With aging, the color of the lens of the eyes change, and the speed of dilation or contraction of the iris slows. Further, the lens of the eye takes on a more opaque coloration. So, glare from reflective surfaces and brightly or dimly lit environments can be problematic since it becomes more difficult for older adults to use their eyes for purposes of communication, let alone for mobility.

In locations where communication is to take place, avoid exposed lighting fixtures, uncovered windows and fluorescent light fixtures. The flicker of fluorescent light can cause tearing of the aging eye, inattentiveness, headaches, and even seizure behaviors in persons who have never before experienced them. Use incandescent lighting whenever possible!

Other types of lighting can cause problems. For example, avoid “mood” lighting, flickering candle light, wall lights, spot lights and corner illumination in homes, businesses, medical offices, and other locations where communication is to take place.

 

Increasing the Intelligibility of Spoken Speech

1. Coach those who are to speak before an audience at a meeting, ministers, even those who read the minutes of the previous meeting on how to speak with greater clarity! This can be done by instructing them to do one simple thing: slow their rate of speech. Adults and children alike understand speech best when it is uttered at a rate of  about 124 words a minute. Public speakers, teachers, family members, or business persons are generally found to speak more like 160-180 words a minute. The human central auditory nervous system is simply not designed to process and comprehend speech that is uttered at that speed (Hull, 2007).
2. If the reader has watched the early television shows of Mr. Rogers’ Neighborhood, or listened to news commentators such as Paul Harvey, Walter Cronkite, or Tom Brokaw, you will observe that one of the important reasons they were so easily heard and understood, and therefore so popular with their audiences, is that they practiced speaking at a rate of around 124-126 words a minute. Advise speakers to emulate those professionals; by slowing their rate of speech, they will increase its clarity.
3. Instruct speakers how to use the microphone. Most microphones in meeting rooms, church sanctuaries, and other places where people congregate are “high impedance” in their design, meaning that they resist the voice signal. They are traditionally preferred in places where other extraneous sounds may be picked up by the microphone, as for example,in the case of a singer in a nightclub with an amplified “back- up” band.Those microphones are designed to be held within 2-3 inches of the mouth. If the amplifier is turned up to compensate for a microphone that is held further from the mouth, “acoustic feedback” will probably occur. Importantly, make sure the PA system is available and used, particularly if there are 15 or more people in the audience.
4. Advise those who are responsible for banquets or other such activities to avoid background music, or MUSAK, in the listening/communicative environment, no matter how one might feel that it will “set the mood” for the event. It becomes a competitor to speech recognition, and interferes with speech understanding.

 

Summary

In order to prevent the possibility of unnecessarily causing otherwise minor impairments of hearing and central auditory function from appearing greater than they are, we must work in terms of supportive architecture, thereby preventing unnecessary impairments of hearing and speech understanding, vision, mobility, social competence, and mental competence.

Older adults do not, of course, want to seem more impaired than they truly in their ability to hear, see, and communicate. But many environments where listening and communication are intended to take place are such that even relatively minor impairments become unnecessarily amplified.

**Information in this article can also be found in a somewhat expanded version in Hull, R.H. (2011). Environmental design—An expanding role in hearing rehabilitation for older adults. Journal of Rehabilitation Research and Development. 48 (5), xv-xviii.

 

 

 

Raymond (Ray) Hull, Ph.D. is Professor, Department of Communication Sciences and Disorders, College of Health Professions at Wichita State University. He is a Fellow of the American Speech-Language-Hearing Association and the American Academy of Audiology, author of six books on hearing loss in adults and children, author of over sixty articles and over 200 scientific presentations and workshops on central auditory changes in aging, the rehabilitation of adults with impaired hearing, and the art of communication in professional practice. His PhD in Audiology/Neuroscience of Communication is from the University of Denver. He has been awarded many citations and honors for his work on behalf of both adults and children with impaired hearing, most recently a Distinguished Service Award by the United States Public Health Service. His latest book is entitled, “Hearing and Aging”, published by Plural Publishing, San Diego.

 

 

 

 

 

 

 

 

 

 

REFERENCES

1. Acoustical design (2010). Available at https://wwwHealth care design magazine.com, June 11, 2010.
2. Anthony, P. (2006). Room acoustics design. Available at https://www.      Forum.acoustics.com/bbs/messages.
3. Hawkins, J. (1973). Comparative otopathology: aging, noise, and ototoxic drugs. Advances in Oto-Rhino-Laryngology, 20, 125-141.
4. Hull, R. (2007). Home make-over. Interview with Advance for speech-language pathologists and audiologists, 17, 6-8.
5. Mercer, D.M.A. (1981). Acoustic design principles. Review of Physics in Technology, 2.
6. Novak, C.A. (2010). Can you hear me? Optimizing learning through sustainable acoustic design. Schools of the 21^st Century. January, 2010.
7. Tinianov, B. (2009). Sound advice for acoustical design. Available at https://www Cbp magazine.com, Oct., 2009.
8. Yoichi, A., Sato, S., and Nakajima, T. (1997). Acoustic design of a concert hall applying the theory of subjective preference. Acta Acoustica, 83, 635-643.