Evaluation of speech perception in patients with ski slope hearing loss using Arabic consonant speech discrimination lists

Abstract

IntroductionCochlear dead regions are regions of the basilar membrane where the inner hair cells and/or associated neurons function so poorly, such that they may be considered dead. Diagnosing patients suffering from ski slope hearing loss should put in consideration the possibility of cochlear dead regions. These patients often miss out high-frequency components of speech, which are consonant sounds (especially fricatives).ObjectivesThe current study was designed to evaluate speech perception of patients with ski slope high-frequency hearing loss on a modified Arabic consonant speech discrimination lists developed at the University of Alexandria and to evaluate the possible effect of high-frequency dead regions of the cochlear partition on such performance.Materials and methodsTwenty patients with ski slope hearing loss were subjected to the Threshold Equalizing Noise (HL) test to bracket cochlear dead regions. The performance of each on the modified Arabic consonant speech discrimination lists was assessed and correlated with the presence or absence of cochlear dead regions and also with their extent if present across a number of spectral frequencies.ResultsThe results of this study showed that the average correct score of ears with no dead regions on the modified Arabic consonant discrimination lists was 75.32%, whereas the score of ears with dead region(s) was 61.19%. According to the extent of dead regions, the average score of ears with dead region at 4000 Hz only was 62.5%, that of ears with dead regions at 2000-4000 Hz was 61.8%, and that of ears with dead regions at 1000-4000 Hz was 56.5%. The highest probability of error in all ears was for the fricatives.ConclusionSpeech tests that emphasize high-frequency speech elements are crucial in determining cochlear functional reserves in a practical manner. Psychophysical tests that investigate dead regions of the cochlea are synergistic to the high-frequency emphasis speech tests.