Hull, Raymond H. PhD
Many public and private listening environments wreak havoc on adults with aging peripheral and central auditory systems. Adults, who may have noted only some difficulty in specific degraded listening environments at an earlier age, may experience extremely frustrating difficulty in these same situations as they age.
Older adults may blame this difficulty on the speaker, when in fact the culprits may be the reverberant characteristics of the meeting room, the anechoic environment of their home, or the combined effects of auditory and visual distractions in a multipurpose room within a health care facility. Without recognizing this possibility, older adults may begin to avoid these places and isolate themselves unnecessarily.
For audiologists to provide constructive hearing rehabilitation, they must become more than conversant with their patients about the challenges and potential solutions regarding environmental design, which has been shown to provide immediate benefits for patients in many instances.
Meeting rooms, classrooms, church sanctuaries and fellowship halls, nursing home all-purpose rooms, auditoriums, bank lobbies, and many other environments are generally not conducive to hearing and understanding speech. They resemble reverberation chambers (too many almost subliminal echoes), or anechoic environments in which sound does not carry well.
These rooms are often square or rectangular in shape with hard floors (tile, concrete, marble, or wood), sheetrock, concrete block, or brick walls, and they frequently have tile ceilings that are sound-reflective. They usually have white boards or blackboards, uncovered windows, glass-covered pictures, and other sound-reflective surfaces. Most church sanctuaries have hard wooden pews, vaulted ceilings, stained glass windows, hard reflective walls, and hard floors, all sound-reflective or reverberant surfaces.
These reflective surfaces cause speech and other sounds to bounce from one surface to another, setting up reverberant echoes that distort sound, particularly complex sounds such as speech. These echoes can play acoustic havoc with impaired peripheral and central auditory systems by distorting the sounds hearing-impaired individuals are attempting to transduce and interpret, particularly if they happen to be wearing hearing aids.
In contrast, homes designed for comfort are generally furnished in such a way that they essentially become anechoic chambers. That is, they do not give sound the life that is needed to travel well because there are few, if any, reverberant characteristics that enhance sound transmission.
It seems intuitive that too much reverberation, or too many echoes, in a listening environment would be bad for speech understanding and that a typical non-reverberant home environment would enhance hearing, but that is not the case. Many homes designed with comfort in mind restrict the movement of sound by absorbing it before it can travel, which deadens it. Soft carpeting, window drapes, soft chairs and sofas, wall paper, and heavily textured ceilings all absorb sound, and a complex acoustic signal such as speech cannot travel far enough to be heard well from any distance or any angle. Because speech comprises an extremely complex set of acoustic signals, it cannot negotiate stairwells (up or down), travel through doorways, move around corners, or find its way through walls to be received clearly enough by the listener and understood well. Music is a less complex signal, and so will travel with at least a fair degree of accuracy in a home environment—perhaps not the words of the song but the melody at least.
In a typical home, speech will not travel well farther than about seven feet in a straight line. If a speaker is farther from the intended listener, it is important that he move within that optimal distance from the listener prior to speaking. This is also a reason to avoid the seats under the balcony in an auditorium or church sanctuary because speech does not travel well in these areas.
ENVIRONMENTAL DESIGN CONSIDERATIONS
It is not necessary to engage in extensive renovations when working to enhance listening environments. Some environmental modifications can be made by the hearing health care provider. For others, the person with auditory difficulties may have to be his own advocate, and suggest changes that will improve the communicative environment for his specific needs. Audiologists and other care providers can also act as a coach to the patient and his family to assist in making simple environmental changes.
A host of ideas are available to help patients by choosing one or two of these strategies that are most appropriate for their individual situation:
Meeting rooms, church sanctuaries, and other common places
The goal here is to reduce reverberation to enhance the transmission and quality of distortion-free speech so that it is more easily heard and understood. The frustrating aspect of a reverberative listening environment is that the room may actually carry the speech signal so well that the individual may experience little difficulty hearing, or so it seems to the listener. He may think he is hearing fairly well, or at least loudly enough, but may have difficulty understanding what is being said due to crowding of the speech signal.
It is important to avoid taking the listening environment from a state in which there is too much reverberation to one that becomes acoustically dead. In other words, the room should not be changed so much that it becomes one without echoes, caused by adding too much absorbency.
* Because these rooms are typically square or rectangular, patients should do whatever is necessary to alter this shape. This can be done by adding light ceiling-to-floor drapes on an expandable curtain rod to one or two corners of the room, creating a rounder shape and reducing reverberation.
* Hang light drapes to the sides of windows (not over the windows), with the length two to three inches above and about six to eight inches below the window. If there are no windows, hang light floor-to-ceiling drapes at a few strategic locations on the walls.
* If the ceiling is higher than most rooms, hang decorative flagging at regular intervals across the ceiling to reduce echoes.
* If soda machines, ice makers, or water fountains are nearby, make sure that the sound is muffled or quieted as much as possible. If neither option is possible, have these items moved to another location.
* If a food preparation area is attached to or near the meeting room, use heavy drapes to block off that area to quiet the noise of pots and pans and people talking. Adding a wall with a sliding door to block off the area is an even better solution.
* Make sure that the PA system is adequate. A poor or unused PA system can be one of the greatest distracters to successful meetings, particularly when there is a speaker for the event.
* When adding to or installing a new PA system, make sure the speakers are as close to the ceiling as possible with polarity reversed. Acoustic feedback will be avoided, and sound will carry more efficiently because it will drop down over the audience. If PA speakers are at floor level, sound cannot easily rise, and it will be blocked by those sitting in the first row.
* Coach speakers on how to speak with clarity. This can be done very simply by telling them to slow their rate of speech. Persons over 60 can understand speech best when it is uttered at a rate of around 124 words per minute. The average person speaks at a rate of around 160-180 words per minute, a speed that the human central auditory nervous system is simply not designed to process and comprehend.
* Instruct speakers how to properly use the microphone. Most microphones in these environments are high impedance, meaning that they resist the voice signal. They are traditionally placed in areas where other extraneous sounds may possibly be picked up, such as a singer in a nightclub with an amplified backup band.
* These microphones are designed to be held within three to four inches of the mouth. If the amplifier is turned up to compensate for a microphone held farther away, acoustic feedback such as a squealing or whistling will be emitted, and can be quite disturbing to listeners. The amplifier and speakers must be far enough away from the microphone to prevent this from occurring.
* Advise those responsible for banquets or other activities to avoid background music, or Muzak. No matter how it will set the mood for the event, it competes with speech recognition, and at the least interferes with speech understanding.
The home acoustic environment may explain why people generally congregate in the kitchen during family gatherings. Conversations can take place with greater ease because kitchens frequently have a harder floor than other areas of the house, and other hard surfaces such as kitchen tables, cupboards, shelves, and stoves further enhance sound transmission.
People generally entertain in the living or family room, but these rooms are typically not ideal environments for conversation, particularly if they contain soft, overstuffed furniture, carpeting, heavy drapes, or textured wallpaper or ceilings.
* While most people cannot ask homeowners to remove the texture and softness of the living environment, some minor changes can be made to enhance the transmission of the speech sounds—replacing heavy carpeting in a room with laminated wood (throw rugs can still be added to keep a feeling of warmth in the room), substituting heavy drapes with window blinds, or exchanging couches and overstuffed chairs with ones that have greater firmness. These changes should not be instituted simultaneously or in the same room, or the environment may become too reverberant.
* Auditory distractions must be reduced. Turn the TV or radio volume down or completely off.
* Do not attempt to communicate with a 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 these obstacles.
* To ensure that the person with whom communication is taking place can hear and understand what is being said, advise others not to speak unless the other person can see the face of the speaker—again, not from another room or while walking away from the listener.
Careful attention must be paid to lighting when altering the environment. With aging, the color of the eye lens changes, and the speed of dilation or contraction of the iris begins to slow. The lens of the eye also takes on a more opaque coloration, so glare and movement from a brighter environment to one with less light or from less light to a brightly lit environment can be problematic because it becomes more difficult for older adults to use their eyes to communicate.
Advise patients to 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 seizures in those who have never experienced them. Incandescent lighting should be used whenever possible.
Other types of lighting can cause problems as well. Mood lighting, candlelight, wall lights, spot lights, and corner illumination in homes, businesses, medical offices, and other locations where older adults are expected to communicate should be avoided. These tend to distort the visual environment for these individuals. Floors covered with no-wax floor polish, polished tile, and highly polished hardwood should also be avoided. Polished linoleum can resemble an ice skating rink to aging eyes, resulting in visual distractions and even possible falls.
THE COLLECTIVE GOAL
Older adults with impaired hearing and aging visual systems do not, of course, want to appear demented or impaired more than they truly are, but the design of many environments can result in what may be relatively minor impairments becoming unnecessarily amplified.
We must provide supportive architecture and practical solutions that will prevent unnecessary impairments of hearing and speech understanding, vision, mobility, and social and mental competence.
Read more on this topic in Dr. Hull's editorial, “Environmental design—An expanding role in hearing rehabilitation for older adults.” (J Rehabil Res Dev 2011; 48;xvxviii; http://bit.ly/HullEditorial.)
© 2011 Lippincott Williams & Wilkins, Inc.