Abstract
Elderly 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 the 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 audiological assessment protocol of
the elderly. The utilization of these tests in the assessment of the elderly enables us to
improve the quality of therapeutic-rehabilitative interventions