Assistive Listening Devices and Systems: Amplification Technology for Consumers with Hearing Loss

Journal of Rehabilitation, July-Sept, 2000 by Alice E. Holmes, John P. Saxon, Holly S. Kaplan

Hearing loss is an invisible disability that affects over 22.5 million Americans (Adams & Benson, 1992). Estimates on the prevalence of hearing loss vary depending on the population studied and the criteria chosen to define hearing loss. Results of a 1987 survey from the Center of National Health Statistics Americans (Adams & Benson, 1992) indicate that 14% of the population in the 45 to 64 year age group has hearing loss. Degenerative changes in the auditory mechanism often accompany advancing age. Hearing loss ranks second only to arthritis in prevalence among chronic problems affecting the physical health of the aged population (Harris, 1978). The prevalence of hearing loss in the elderly population has been estimated to be between 25% to 80% with the wide range explained by differences in the criteria employed and the sampling criteria (Davis, 1989; Gates, Cooper, Kannel & Miller, 1990; Milne, 1976). In addition, Niskar et al. (1998) found that 14.9% of the children between the ages of six and 19 years evaluated in a national study had some degree of hearing loss. These statistics highlight the need for professionals in rehabilitation to be knowledgeable in devices that may help their clients deal with communication problems that accompany hearing loss.

Amplification in the form of hearing aids is the primary rehabilitative tool the audiologist has to offer an individual with a hearing loss. Although the benefits of hearing aids in the population with hearing loss are well documented (Harless & McConnell, 1982; Kricos, Lesner, Sandridge & Yanke, 1987; Malinoff & Weinstein, 1989; Mulrow, et al., 1990), factors such as the presence of background noise and distance from the speaker or sound source can reduce the amount of benefit received from traditional heating aids.

Assitive listening devices (ALDs) have been developed to help individuals in communication and environmental setting when hearing aids are insufficient. The purpose of the article is to present the advantages and disadvantages of ALDs, audiologist assessment and rehabilitation counseling considerations, and a discussion of types of assistive listening devices.

In 1990, the Americans with Disabilities Act (ADA) provided the legislative foundation to vastly expand legal rights of individuals who have disabling conditions (Public Law 101-336). The ADA is composed of five titles covering the areas of employment, public services, and programs and communication. Private employers, state and local governments, and public accommodation establishments are covered under Titles I, II, and III (Strauss, 1994). Of paramount importance are the phrases 'qualified individual with a disability, who with or without reasonable accommodation, can perform the essential functions of the employment position.' Reasonable accommodation are considered those that do not place an 'undue hardship' on the business.

The Department of Justice in its regulations concerning Title II, provides a list of aids and services for individuals with hearing impairments:

   '[q]ualified interpreters, notetakers, transcription services, written
   materials, telephone handset amplifiers, assistive listening devices,
   assistive listening systems, telephones compatible with hearing aids,
   closed caption decoders, open and closed captioning, telecommunications
   devices for deaf persons (TDD's) [and] video text displays....' [28 C.F.R.
   [sections] 36.303(b) (1)]

Holt and Seeger (1995) studied 390 individuals who were admitted to a rehabilitation unit of a hospital. The subjects were divided into six age groupings: less than 40 age group (n=11), 40-49 age groups (n=31), 50-59 age group (n=35), 60-69 age group (n=107), 70-79 age group (n=134), and over 80 age group (n=72). They found that hearing loss was related to the age group with poorer hearing in the older groups. The most common hearing impairment across age groups was in the mild to moderate range. They state, 'this type of hearing loss is very difficult to identify without formal audiological evaluation.' (p. 59) An individual with mild to moderate hearing loss may not have difficulty communicating in a quiet environment, but have significant difficulty communicating in a noisy environment. This could account for the fact that twenty-two percent of the subjects in this study who had a significant hearing impairment denied any hearing difficulty. Smith and Kampfe (1997) point out that hearing loss not only caused pronounced modifications in relationships and interpersonal functioning, but also causes fatigue, isolation, reduction in recreational activities, anxiety, fear and distrust.

Assistive listening devices (ALDs) are various types of amplification equipment designed to improve the communication of persons with hearing loss in instances where traditional hearing aids are not sufficient. These assistive devices can facilitate listening in noisy environments and group conversations. They also can improve distance listening and help in alerting to and identifying important warning signals both on and off the job.