Analogue and Digital Hearing Aids. (Part 2). Audiometric Findings andRelationship to Subjective Evaluation of Hearing Aids

Overview

In a group of 114 patients, incl. 87 with analogue and 27 with completely digital hearingaids the authors analyzed findings of speech audiometry without and with the hearing aid. Theyused as a basis the previous analysis of subjective evaluation of hearing aids by the patients bymeans of a questionnaire. They evaluated speech audiograms made during selection and allotmentof the hearing i.e. before they patient got used to it. The authors evaluated the threshold ofperception and maximum perception with the hearing aid and the resulting value of these parameters in dB and in four comparable groups of analogue and digital hearing aids (behind the earhearing aids for medium, severe and very severe losses and hearing aids inserted into the auditorycanal). A method of correction was elaborated for evaluating improvement of perception in patientswho did not attain 100% or not even 50% in speech discrimination. In general better results in speechaudiometry were achieved with digital hearing aids which is consistent with the subjective evaluation of hearing aids by patients. Statistically significant differences were confirmed only in thegroup of suspended hearing aids for medium severe losses (p = 0.006, p = 0.039). The authors areaware of the fact that mixed speech audiometry in a quiet environment has restricted possibilitiesas regards evaluation of the advantages of digital and analogue technology for perceiving speech.However they do not possess a test which can be evaluated better by statistical methods. It was alsofound that patients who use their hearing aid more often (for longer periods of the day) achieveda greater improvement of the threshold of perception and maximal perception with the hearing aidduring speech audiometry than patients who use the hearing aid only rarely (p = 0.001, and p = 0.006resp.). This indicates that it is justified to use speech audiometry in a quiet environment as one ofthe criteria for the selection of hearing aids. The authors did not prove a significant sexualdifference as regards improved perception. When investigating the effect of the patients’ age onimproved perception of speech with the hearing aid there was only one significant correlation, i.e.a less marked improvement of speech receptia threshold in older patients (p = 0.035). It seems thatphysiological ageing has a relatively small impact on the asset of the hearing aid at least in a quietenvironment.

Key words:
hearing aid, analoque and digital, speech audiometry, age, sex.