Development and evaluation of a free-field voice test for potential use as a community screening tool for hearing impairment in children

Master Thesis


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University of Cape Town

Early identification of hearing impairment in children is essential to avoid potentially disabling effects of hearing loss or deafness. This necessitates effective screening measures appropriate to the community in question. Current methods used in South Africa, especially for pre-school and school going children have resulted in poor coverage as they are designed for the more developed countries. There is thus a need to devise a screening method that is appropriate to our local conditions. In this study, a free-field live voice test was developed based on three levels: whisper, conversational and loud. This was evaluated against pure tone audiometry for sensitivity, specificity, cost and ease of application in two studies: hospital and school- based. A total of 394 children were tested; 189 in hospital-based study and 205 in school based study. 378 of the total were eligible for analysis. In the hospital-based study, the results of 177 children were analysed. The age range was 3 - 12 years with a mean of 5.8 years. The sensitivity (ability of the test to detect hearing impairment) was 80.0%; and the specificity (ability to identify children with normal hearing) was 95.0%. In the school-based study, done after modification and standardisation of the test set, the sensitivity and specificity were 83.3% and 97.8% respectively. Age range was 3 - 8 years with 79% being 4- 6 years. In both studies, the voice test was simpler to perform, easily understood and acceptable to the children and the testers; and considerably cheaper as the only equipment required was picture/toy set. The main limitation was non-standardisation of the test set. This was rectified in the school-based study. The drawbacks noted were the inability of the voice test to detect unilateral hearing loss/deafness and high frequency hearing loss. The voice test generally correlated well with pure tone audiometry and could be used as alternative for screening for hearing impairment in the community especially for pre-school and school going children. However, it is recommended to repeat the study in actual community settings using Community Health Care Workers as the testers. This would also determine the reliability of the voice test, as this cannot be reliably established at this stage.