Screening for Hearing Loss
in the General Population
Lynn S. Alvord Ph.D.
There are two vast populations for which hearing loss is of major prevalence - young children and aging adults. It is estimated that between 30 and 50 percent of the population past 65 years of age is affected by
significant hearing impairment (1), yet only 13 to 18 percent of the elderly hearing-impaired use a hearing aid (2, 3).
Though hearing loss is also very prevalent in young children, typical age of detection is not until between the ages of 3 and 7 years (4).
For the elderly, hearing loss causes many psychosocial and emotional changes. Many authors have reported the value of communication to a person's social, intellectual and emotional well-being (5). The isolation caused by communication disorders may be unbearable, health may be affected and mental state deteriorates at a more rapid degree.
The hearing impaired often withdraw socially, not wishing to draw attention to their disorder, and may be mistakenly categorized as less intelligent, shy, learning disabled or lacking in motivation.
For the young child, language, reading and general learning is delayed, even for mild hearing losses (6).
Late or delayed identification is the major stumbling block to remediation. Possible causes for such delays are:
1. Hearing loss is often gradual in onset, rendering the victim unaware. Slow onset also increases the denial process.
2. There is lack of understanding of the nature of hearing loss among health and education professionals ("Audiology" the study of hearing, is a relatively young science).
3. Equipment for hearing screening, until
recently, has been bulky, expensive and difficult to use.
Evidence of these factors is born out by the experience of many who undergo a complete physical examination without consideration for hearing loss.
Although blood pressure, reflexes and vision (eye chart) are often screened, hearing is rarely checked by physicians. The often stated excuse is that the patient will likely point out a hearing loss to the physician. Considering the slow, insidious nature of the disorder, this is unlikely.
Children are often screened at school but not typically before kindergarten and then only every other year. since peak age for learning language is 2 1/2 years and most ear infections occur prior to age 4 (6), such a screening scenario is far from adequate.
Purpose
Studies were undertaken to assess the adequacy of newer miniature screening devices and noise
environments under which screenings may be performed. Ambient noise was measured in physicians' offices and compared to recommended background levels for screening. Accuracy of a miniature hand-held audiometer was compared to that of standard full-scale equipment used in a sound proof booth.
Methods
Background noise was monitored in 20 physician offices in the Salt Lake City area. Two 20 minute averaged measurements were taken using a Larson-Davis sound level meter and Hewlett Packard microcomputer (71B). Next, the hearing of 50
patients was tested both with a small hand-held audiometer (Handtronix-OtoScreener) and standard audiometer and test booth. Sensitivity and specificity of the small screener was judged based upon comparison to the "true" test utilizing standard equipment. Hearing was screened at a
level of 20 dB HL (re: 1969 ANSI) (7).
Results
Table 1 shows agreement between the small and standard audiometer. "Sensitivity" refers to ability of the screener to correctly detect hearing loss (93%). "Specificity" or ability to correctly pass those without loss was 85.7%. False positives, those without loss but shown to be abnormal by the screener was 14.3%, while false negatives, those with true losses missed by the screener, was 6.9%.
Noise measurements in physicians' offices are shown in Table 2, and then compared to allowable levels for screening at 20 dB (Table 3). According to the guidelines of the American Speech-Language-Hearing Association (ASHA) the following octave band room noise levels are allowable for screening at 20 dB: 41.5 dB at 500 Hx, 49.5 dB at 1000 Hz, 54.5 dB at 2000 Hz, and 62.0 dB and 4000 Hz (dB SPL re.0002 dynes/cm2 ) (8). The ASHA recommendations call for screening at 20 dB for children (500, 1000, 2000, and 4000 Hz) (9). Ventry and Weinstein recommend screening the geriatric population at 40 dB (1000 and 2000 Hz only) (10), however, other authors feel the aging population should be screened at the same criteria as a younger population (11).
Discussion
according to these results, noise is sufficiently low to allow screening at all but 500 Hz in virtually all offices tested. The inclusion of 500 Hz is considered less than necessary since the latest ASHA proposal will omit 500 Hz from the protocol. also, results show accuracy of the smaller hand-held audiometer to be quite high (93% sensitivity).
These results lead to the conclusion that screening may be performed easily, accurately and inexpensively in nearly any typical (quiet) enviroment such as a physician's examination room. Therefore, expensive equipment such as a sound treated booth is not necessarily a prerequisite for accurate screening provided precautions are taken to maintain quiet.
Conclusions
The implications of early detection of hearing loss are far reaching. For the child, adequate hearing is a essential to normal language development and classroom learning. For the aging adult, prompt identification of impairment can lead to remediation through hearing aids and other rehabilitation processess.
As stated in the introduction, hearing loss extremely prevalent among the very young and aging populations. The high numbers of individuals possessing this disorder necessitates a growing awarenes and willingness to deal with the problem. Since screening is a simple procedure, programs may be initiated and executed by non-health professionals. An audiologist is the professional best qualified to oversee and administer such programs. Early identification of hearing loss through screening will lead to more effective and timely remediation of this pervasive social problem.
