Changes in the significance of maternal rubella as a factor in childhood deafness--1954 to 1982.

The previously reported reduction in rubella-related congenital deafness in Australian children born since 1977 has been confirmed by a survey of hearing-aid fittings for rubella-related deafness among those born from 1954 to 1982. Analyses of these figures also showed that in more than 50% of individuals born during the period 1954 to 1975, rubella deafness had not been recognized as such, and that mild-to-moderate deafness was a more frequent outcome of maternal rubella than was severe or profound deafness. A prediction has been made of the expected total incidence of hearing-aid fittings to children when rubella accounts for a far smaller percentage of the cases of deafness than in previous years.

Children with hearing aids in the 1980s: etiologies and severity of impairment.

The value of 20 years of attempts to control the causes of hearing impairment in children should now be observable. If they have been successful there can be expected to be a change in the prevalence of some etiologies, a variation in the proportions of all remaining etiologies, and a reduction in the prevalence of severe and profound impairments. An investigation of these expectations has been conducted by surveying children fitted with hearing aids in Australia. The results of this investigation highlight development of a number of new trends, including virtual elimination of maternal rubella and Rh incompatibility as causes of impairment, together with a new emphasis on the fitting of hearing aids for mild and conductive impairments.

The early detection of childhood deafness.

Early commencement of habilitative measures is vital for a deaf child's development. This implies a need for early diagnosis. Some improvement has occurred in recent years, but early diagnosis is still the exception rather than the rule. To determine some of the factors which lead to early diagnosis, a survey of parents of young Australian deaf children was undertaken. This showed that, while the majority of children were suspected to be deaf on the basis of informal observation by parents, relatives or friends, the most consistent early diagnosis came as a result of follow up of infants at risk. Certain factors acted to delay diagnosis. Dissuasion and inappropriate advice from doctors significantly delayed diagnosis in 25% of all cases. Further, over half the hearing-impaired children who were tested in screening programmes were not detected, and the false sense of security given the parents in these cases resulted in long delays before suspicion of deafness (based on informal observation) developed. If early diagnosis of deafness is to become the rule, a purposeful attempt to use risk criteria, coupled with improved screening programmes, will be the most promising avenues to follow. Improved education of the community at large may also assist, but this is a much longer-term aim.

The evaluation of CROS aids with the unilateral listener.

The CROS hearing aid, originally designed to assist persons with one normal and one unaidable ear, has according to most reports been of most value when the better ear also requires amplification. The most common complaint from normal-hearing users has been excess noise and masking via the aid. While the problem is obviously complex, one of the major factors, that of in the ear performance, has not been adequately analysed. The amount of gain provided by the CROS system, which is closely related to excess noise and masking, is usually not evaluated. A method of evaluation which reflects the change in CROS-aided threshold values, rather than the more usual above-threshold performance is presented. This procedure, based on masked sound field thresholds, has a number of advantages. An example, using six cases, is presented to illustrate the method and its results.

Hearing-aid fitting protocol.

A five appointment programme protocol for hearing-aid selection, fitting and client guidance is described. The full protocol requires a maximum work load average of 3 h per client, and is appropriate for the vast majority of psychologically and physically intact first time aid users. Drawn up for use mainly with an elderly population, the protocol is equally appropriate with younger adult clients contacts over a relatively short time to allow repetition and reinforcement and develop motivation. Each appointment has been designed to contain a proportion of instruction, a proportion of assessment and evaluation, and a proportion of advice and guidance. Clients proceed in accordance with individual capacity, but do not proceed beyond any point until performance is verified. A number of recently developed methods are incorporated into the protocol. These include methods of aid selection, ear impression taking, aided threshold testing and validity checks and speech test selection.

Childhood deafness in Australia. Incidence and maternal rubella, 1949-1980.

A survey of children born between 1949 and 1980 who are known to have been fitted with hearing aids in Australia by the age of 18 years reveals a ratio of 2.605 cases for every 1000 liver births. This incidence of childhood deafness is higher than previously reported, as a result of the greater number of birth years considered. Approximately 41.2% of these children have severe or profound deafness. A history of maternal rubella was reported in 11.06% of cases, but a significant reduction in the number of reported rubella cases after 1976 has led to correspondingly fewer diagnoses of severely and profoundly deaf children.

Hearing-aid use and available aid ranges.

The assertion that a wide range of hearing aids is necessary in auditory rehabilitation has frequently been made, but little evidence has been offered as support. Further, little explanation has been offered as to the constitution of an adequate range of aids, nor what determines the adequacy. Comparisons of use rates of two large populations of people, one fitted from a wide range of aids and the other from a narrow range, provides some information on the relationship between extent of the aid range available and the results of fitting. The conclusion is reached that fitting methods and procedures appear to be more significant than aid range in ensuring that hearing aids are used consistently.

Hearing aid manipulation skills in an elderly population: a comparison of ITE, BTE, and ITC aids.

In-the-ear, in-the-canal and behind-the-ear hearing aids were compared for ease of management by elderly people. Two hundred and forty-four clients were randomly assigned to be fitted with one aid type, and rated for ability to perform the manipulative tasks necessary to enable effective use of the aid. It was found that in-the-ear aids were easiest to use, that females experienced greater difficulties in manipulation than males and that some tasks were easier to perform and more quickly learned than others. The findings are discussed in terms of design requirements and aid fitting practices.

The advantages and disadvantages of ITC, ITE and BTE hearing aids: diary and interview reports from elderly users.

The advantages and disadvantages of in-the-canal (ITC), in-the-ear (ITE) and behind-the-ear (BTE) hearing aids for elderly aid users were examined. Two hundred and forty four clients were randomly assigned to one of the three aid types from seven hearing aid manufacturers. The clients' perceived help from their fitting, and the degree of difficulty they encountered over a range of listening situations and environments were rated using a daily diary and a structured interview. Findings indicated that for elderly clients there were no large practical advantages for one aid type over another. While ITC and ITE aids were rated more highly than BTE's in background noise, all three aid types were rated as relatively poor in background noise as well as in groups, in the wind, when using the telephone and in the localisation of sound. All three aid types were rated equally and well for performance in one-to-one conversation in quiet, and for listening to television and radio. Hours of use and reasons for non-use are presented, as are clients' reports on cosmetic issues, manipulative ease and overall satisfaction level with their aids.

Epidemiology of congenital rubella and results of rubella vaccination in Australia.

Congenital rubella was not notifiable in Australia until recently, but the national incidence of childhood deafness has been accurately documented since 1949. On the basis of these data and a study of congenital rubella in Western Australia, it is estimated that the national incidence of congenital rubella has decreased from a mean of at least 120 cases annually (one in 2,000 live births) to approximately 20 or less since 1977. This decrease has occurred since the introduction of rubella vaccination programs in 1971. The aim of these programs was to reduce the incidence of congenital infection by vaccinating girls (aged 10-14 years) at school without assessing their immunity. Nonpregnant seronegative women were also offered vaccination in family planning clinics as were postpartum seronegative women in obstetric units. By 1983, 96% of 8,226 pregnant women were seropositive for rubella antibody, as compared with only 82% of a similar group of women in 1971. This improvement in the immune status of pregnant women appears to be the result of rubella vaccination. Rubella vaccination also appears to have been successful in preventing congenital infection.