This report was prepared by the American Speech-Language-Hearing Association (ASHA) Committee on Amplification for the Hearing Impaired. Present and past committee members responsible for this report include Thomas S. Rees, current chair; Walt Smoski, past chair; G. Jean Boggess; Evelyn Cherow, ex officio; Alice E. Holmes; Barbara J. Moore-Brown; Polly E. Patrick; Valenta G. Ward-Gravely; Linda Van Dyke; and Peter Ivory. Teris K. Schery, 1988–1990 vice president for clinical affairs, was monitoring vice president. The ASHA Executive Board accepted the report in August 1990 for publication in Asha (EB 116-90).
The use of various amplification devices for populations other than those with hearing disorders—that is, for persons with normal peripheral hearing—has been reported as a therapeutic tool in recent years. This type of habilitation/rehabilitation has been suggested for use primarily with children in educational and clinical settings as a remedial technique for those with phonological disorders, central auditory processing disorders (CAPD), and language/learning disabilities. The goals of such intervention include increasing attention span, reducing distractibility, improving signal-to-noise ratio, and increasing sound (phonological) awareness and discrimination. This application is apparently based on the premise that the development of these skills affects children's speech sound production, language processing, and academic achievement. The committee is responding to questions and concerns that have been raised regarding the efficacy of this practice and potential detrimental effects on hearing. The limited literature addressing the use of amplification with children who have normal peripheral hearing is reviewed in this report. Finally, concerns about clinical practice and recommendations for further research needs are offered.
Amplification for the purpose of increasing the intensity level of stimulus presentation in order to improve response accuracy has been reported to be effective in several studies. During the development and evaluation of the Northwestern University Children's Perception of Speech Test (NU-CHIPS), Elliot and Katz (1980) reported that normal-hearing 3-year-olds required increased intensity levels during stimulus presentation to reach criterion on a picture-naming task. In a subsequent study, normal-hearing 6-and 10-year-olds required higher intensity levels than adults to identify Consonant-Vowel (CV) syllables (Elliot, Longinotti, Clifton, & Meyer, 1981). A higher stimulus presentation level also was reported to be necessary for children with articulation disorders to achieve more accurate productions when compared to those without articulation disorders (Clifton & Elliot, 1982).
Intervention programs for children with articulation or phonological disorders have included ongoing or intermittent use of amplification devices. Shriberg (1983) recommended the use of “augmented input” as an integral component in articulation programs for children. Hodson and Paden (1983) described a 2-minute period of auditory bombardment with amplification at the beginning and end of each session in the treatment of phonological disabilities. Stimulus words targeting specific phonemes were read to children using a “low level of amplification.” Hodson and Paden stated that children with phonological disorders benefited from a program including emphasis by intense presentation of sounds and sound sequences. Amplification was felt to direct the child's attention to the target and to be more successful than other methods for improving the production of sounds. The authors emphasized the use of “low level amplification” and stated that “caution must be taken to keep the level minimal…in order to avoid any possible damage to the child's hearing mechanism” (p. 50).
FM assistive listening devices also have been used as a possible intervention strategy for children with central auditory processing disorders. Stach, Loiselle, and Jerger (1987) reported on 25 such children who were given a trial period with FM systems set to minimal gain, 11 of whom were subsequently fit with the devices. The parents and teachers of these children stated that they observed improved academic and behavioral performance. Stach, Loiselle, Jerger, Mintz, and Taylor (1987) also reported on a single case study of a 7-year-old who was fit with an FM device. Improved academic achievement and modification of behavior were noted by parents and teachers.
The use of low-power FM wireless systems for children with learning disabilities has been described in two reports by a manufacturer. The first involved using FM systems with learning-disabled children from 6- to 12-years of age for 30 minutes to 2 hours per day for 3-6 weeks (Loose, 1984). Teachers reported that the students appeared to show increases in attention, productivity, and accuracy. The second manufacturer's report involved 40 normal hearing 5- to 10-year-olds who were judged to have attention problems (Blake, Torpey, & Wertz, 1986). Twenty of the children used auditory trainers during instructional periods for 24 weeks, and the other 20 served as a control group. Pre– and post–intervention observations for target behaviors were made for both groups. Statistical analyses were not reported; however, preliminary findings indicated that 95% of the experimental group demonstrated improved attending behavior (e.g., increased eye contact with teacher, increased rate and appropriateness of response, increased ability to follow directions, and increased awareness of verbal cues, body position, and body control). In addition, decreased body movement and reduction in extraneous verbalizations and distractibility were also noted.
Shapiro and Mistal (1985) reported on the use of high-frequency amplification in reading- and spelling-disabled children. Four reading-disordered children, 2 with normal hearing and 2 with hearing loss at 6,000 Hz and 8,000 Hz, were fit with an in-the-ear (ITE) hearing aid in the right ear. Use of amplification reportedly enhanced only the frequencies between 2,500 Hz and 6,000 Hz, although no functional or real ear measurements were reported. The authors reported an improvement in the areas of auditory memory, articulation of complex words, and intelligibility of phonetically balanced words. A subsequent study (Shapiro & Mistal, 1986) evaluated the long-term effects of high-frequency amplification. Fourteen normal-hearing students referred for reading/spelling delays were divided into 2 groups: 7 were fit with high-frequency ITE's, and 7 served as a matched control group. After 13 months of use, testing of the unamplified group did not show any group differences in spelling, reading progress, or speech discrimination; however, the amplified group showed an enhancement in speech discrimination in noise over the unaided condition. The amount of gain provided by the ITE's was not specified.
Project MARRS (Mainstream Amplification Resource Room Study) (Sarff, Ray, & Bagwell, 1981; Ray, Sarff, & Glassford, 1984) was the first study to report the use of sound field amplification for children with academic achievement deficits. Fourth-, fifth-, and sixth-grade classes in four schools were equipped with an FM teacher transmitter and two speakers that provided amplified speech at intensity levels of approximately 10 dB above the ambient noise level. Target students were selected using the following criteria: each student had a minimal hearing loss (15 dB to 35 dB HL), had academic deficits of 6 months or more, and had average intellectual potential. Half of the target students were placed in amplified classrooms; the other half were placed in unamplified classrooms and received supplemental instruction from a resource room teacher. The target students were not identified for the teachers. Typical use of the sound systems was 3 hours per day. Students received 1, 2, or 3 years of treatment. The results indicated that target students in amplified classrooms demonstrated significantly improved Scholastic Reading Achievement scores, and this increase was equal to or greater than that of the target students who received resource room instruction. Additionally, regarding the MARRS project, Ray (1987) stated that, “questionnaire data obtained from administrators, teachers, and students indicated the intervention is helpful to teachers and to non-handicapped students as well as those with mild hearing losses” (p. 14).
Flexer (1989) reported results obtained from another school system utilizing 47 sound field amplification systems in regular classrooms. The educators had found that 43% of primary-level students failed a 15 dB HL hearing screening considered to be educationally significant. After 3 years of use, results indicated that even though pupil count had increased in the school, the number of students receiving special services had decreased from 945 at the beginning of the study to 850 after amplifying the classrooms. In general, higher scores were obtained on the Iowa Test of Basic Skills for students in amplified classrooms in kindergarten through third grade. Teachers reported improved on-task behavior, improved use of voices, use of longer utterances, and increased confidence when using the microphone.
Although this review has focused on children with normal peripheral hearing, the use of assistive listening devices with normal-hearing head-injured adult clients was addressed by Casterline, Flexer, & DePompei (1989). They reported decreases in distracting behaviors and increased attention.
The current literature leaves several questions unanswered regarding safety and efficacy in the use of amplification devices on children with normal peripheral hearing. Several concerns arise related to this practice.
Although the literature cited has suggested benefit with the use of amplification in individuals with normal peripheral hearing, conclusions were based primarily on anecdotal reports in non refereed publications and without specific empirical data to support the investigators' conclusions.
Specific data regarding the gain provided, the acoustic environments in which amplification was used, the cumulative wearing time, and the method of selection and fitting were not reported and are essential. Research is needed in controlled settings to eliminate extraneous factors that have threatened the internal validity of previous findings. In addition, information about the involvement of audiologists in the methodology described is absent in the current literature.
Risk management practices dictate that caution be exercised in the fitting of any amplification device because of the potential for noise-induced hearing loss. The potential for damage to the normal auditory mechanism through exposure to intense sounds is well-documented. The Occupational Safety and Health Administration (U.S. Department of Labor, 1983) warns that adults who are exposed to noise levels at or above 85 dBA for an 8 hour time-weighted average are at risk for noise-induced hearing loss. As the intensity of the sound increases, the acceptable exposure time decreases dramatically. For example, the maximum allowable exposure levels for occupational noise are 90 dBA for 8 hours, 110 dBA for 30 min., and 125 dBA for less than 4 min.
It is not uncommon for personal hearing aids and amplification systems to produce 135 to 145 dB SPL at the tympanic membrane. More conservative levels are advisable with children, who have been reported to be at greater risk for incurring noise-induced hearing loss than adults (Humes, 1988; Mills, 1975). Although many amplification devices are marketed as mild gain instruments, the actual peak output of these instruments may vary depending on such factors as input level, distance from the microphone, and receiver coupling. Because younger children have smaller ear canal volumes, the sound pressure level (SPL) at the tympanic membrane may be even higher than in adults (Jirsa & Norris, 1978). Only real ear measurements with the device on the child can assure that excessive SPL's are not being produced.
Currently, there are no uniform procedures for the selection and fitting of amplification devices other than personal hearing aids. Procedures need to be developed that include the real ear measurement of SPL delivered to the ear and measurement of discomfort levels. Traditional coupler gain or functional gain measurements are not appropriate with children who have no peripheral hearing loss. Consumer protection and the qualifications of professionals responsible for recommending amplification devices on persons with normal peripheral hearing need to be addressed. Close monitoring of the electroacoustic properties of these devices and of the thresholds of the children wearing them is essential. Selection and monitoring of these devices are the responsibilities of a licensed or certified audiologist (ASHA, 1984).
The use of amplification devices including FM systems, auditory trainers, personal amplification devices, and other assistive listening devices with normal-hearing children who have disorders of articulation, auditory processing, language, and learning has been reported. This practice raises three areas of concern: efficacy, consumer safety, and professional liability. Well-designed research is needed to evaluate the efficacy of using amplification with normal-hearing individuals. These studies should be carefully controlled for factors that would influence the validity of the research. The issue of potential damage to the auditory mechanism should be considered when fitting any amplification device. Instruments that improve the signal-to-noise ratio may be an alternative when treating normal-hearing children with special needs. Finally, whenever personal hearing aids or assistive listening devices are being utilized, a certified or licensed audiologist should be involved as a member of the research or clinical team. This committee urges collaborative research among audiologists, speech-language pathologists, and educators to evaluate the efficacy, safety, and associated risk management when using amplification as a remediation technique for children with normal peripheral hearing.
Casterline, C., Flexer, C., & DePompei, R. Use of assistive listening devices with head injured survivors. 1989. Paper presented at the meeting of the American Speech-Language-Hearing Association, St. Louis, MO.
Loose, F. (1984). Learning disabled students use FM wireless systems. Telex Communications. Mills, J. H. (1975). Noise and children: A review of literature. Journal of Acoustical Society of America, 58, 767–779.
Ray, H., Sarff, L. S., & Glassford, J. E. (1984, Summer/Fall). Sound field amplification: An innovative educational intervention for mainstreamed learning disabled students. The Directive Teacher, 18–20.
Stach, B. A., Loiselle, L. H., & Jerger, J. F. FM systems used by children with central auditory processing disorders. 1987, November. Paper presented at the annual convention of the American Speech-Language-Hearing Association, New Orleans, LA.
Index terms: amplification
Reference this material as: American Speech-Language-Hearing Association. (1991). Amplification as a remediation technique for children with normal peripheral hearing [Technical Report]. Available from www.asha.org/policy.
© Copyright 1991 American Speech-Language-Hearing Association. All rights reserved.
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