Central auditory functions in elderly individuals

Abstract

AbstractElderly individuals often have more difficulty in understanding speech than younger adults, particularly in noisy environments. Three models that attempt to explain this are as follows: (a) deterioration in peripheral hearing; (b) structural changes to the central auditory system; and (c) changes in normal cognitive processes. The aim of this study was to assess the central auditory functions in an elderly population and compare them with those of an adult population. Participants and methods The study group included 60 elderly individuals; they were older than 60 years of age and were divided into two subgroups: the first subgroup A included 24 elderly individuals with normal peripheral hearing and the second subgroup B included 36 elderly individuals with presbycusis with a mild degree of hearing loss. The control group included 30 individuals ranging in age from 18 to 30 years. Both the study and the control group were subjected to an otological examination, immittancemetry, pure tone audiometry, speech audiometry, and central auditory processing assessment using the following selected few behavioral central auditory tests: synthetic sentence identification test with ipsilateral competing message (SSI-ICM), dichotic digits test (DDT), auditory fusion test-revised (AFT-R), and pitch pattern sequences test (PPT). Results There were elevated hearing thresholds at mostly all frequencies with statistically significant differences on comparing both study subgroups A and B with the control group. On using SSI-ICM, in the competition ratio (−15 dB), there were statistically significantly low scores in subgroups A and B compared with the control group. Results of DDT showed statistically significantly low scores on comparing the results between the left ear and the right ear in both subgroups A and B. There was a statistically significant elevated gap threshold for tonal stimuli in the AFT-R test on comparing both subgroups A and B with the control group. The results of PPT showed that subgroup B obtained a statistically significantly lower score compared with the control group. There was a statistically significant negative correlation between age and the results of SSI-ICM in the competition ratio 0 dB when presented to the left ear, DDT, and PPT. There was a statistically significant positive correlation between age and the results of AFT-R when presented at 4000 Hz. Conclusion Age-related changes to auditory processing will occur in most adults 60 years of age and older that may or may not be concomitant with peripheral hearing loss. Aging decreases the capacity of digit recognition and also increases interaural asymmetries. Many older listeners show reduced temporal resolution even when potential influences of hearing loss are absent. Temporal ordering abilities decrease with age. Recommendation It is important to include central auditory tests in the audiologic assessment protocol of the elderly. The utilization of these tests in assessment of the elderly enables us to improve the quality of therapeutic-rehabilitative interventions.