Dips on Békésy or audioscan fail to identify carriers of autosomal recessive non-syndromic hearing loss

Bekesy and audioscan sweep audiometry tests were carried out in 24 presumed obligate carriers of autosomal recessive non-syndromic hearing loss and 30 sex and age appropriate controls, with a view to defining the most expedient criteria for dips on either test in respect of possible carrier detection. On Bekesy, dips with a minimum depth of 22.5 dB generated the greatest difference between carriers and non-carriers, while on audioscan, the criterion of a minimum dip depth of 15 dB provided the best discriminant. Using these criteria, the prevalence of dips was also evaluated in 8 unaffected siblings and 24 age appropriate control subjects. The findings both in the adult and the paediatric groups do not support the hypothesis that the presence of dips, either on Bekesy or audioscan, is linked to the carrier state in ARNSHL.