Speech-in-Noise Performance and Executive Functioning in Individuals with Chronic Subjective Tinnitus

Background: Many individuals with chronic subjective tinnitus report significant problems in comprehending speech in adverse listening situations. A large body of studies has provided evidence to support the notion that deficits in speech-in-noise (SIN) are prevalent in the tinnitus population, while some studies have challenged these results. Notably, elemental auditory perception is usually only minimally or not impaired. In addition, deficits in cognitive functions, particularly executive functions, have also been observed in individuals with tinnitus.Methods: In order to investigate differences in SIN performance and executive functioning, 25 participants with tinnitus and 25 control participants, between 23 and 58 years of age, were examined. A large audiometric battery was used, including tests of peripheral and central hearing, ranging from threhold and supra-threshold tasks to complex speech tasks. Additionally, four cognitive tests were performed, primarily covering the area of executive functions. Tinnitometry and tinnitus-related questionnaires were assessed to complement sample description and allow for secondary analyses. The groups were case-matched for age, sex, education, and hearing loss. We hypothesized, that tinnitus participants score lower in SIN and executive function tasks compared to healthy controls, while no group differences in elementary audio tasks were expected.Results: Hypothesized considerable differences in speech perception under adverse listening conditions were found in the SIN task and also in the gated speech task, while there were no differences in the basic speech recognition threshold task. Other elementary auditory perception tasks did not differ between the two groups. The cognitive tests revealed clear deficits in interference susceptibility in the Stroop task, but not in the Flanker task. There were no differences in inhibition or working memory tasks.Conclusion: Our results clearly delineate differences between the tinnitus and the control group in two tests of speech intelligibility under complex listening conditions. Further, the poorer performance in a task of interference control in individuals with tinnitus points towards a reduced central executive control in tinnitus. Taken together, these novel corroborating evidence supports the view of a deficient central inhibiton system in healthy individuals with tinnitus. Hence, we present important contributions to the ongoing debate about the effects of tinnitus on comprehension in adverse listening situations

Functional Age-Related Changes Within the Human Auditory System Studied by Audiometric Examination

Age related hearing loss (presbycusis) is one of the most common sensory deficits in the aging population. The main subjective ailment in the elderly is the deterioration of speech understanding, especially in a noisy environment, which cannot solely be explained by increased hearing thresholds. The examination methods used in presbycusis are primarily focused on the peripheral pathologies (e.g., hearing sensitivity measured by hearing thresholds), with only a limited capacity to detect the central lesion. In our study, auditory tests focused on central auditory abilities were used in addition to classical examination tests, with the aim to compare auditory abilities between an elderly group (elderly, mean age 70.4 years) and young controls (young, mean age 24.4 years) with clinically normal auditory thresholds, and to clarify the interactions between peripheral and central auditory impairments. Despite the fact that the elderly were selected to show natural age-related deterioration of hearing (auditory thresholds did not exceed 20 dB HL for main speech frequencies) and with clinically normal speech reception thresholds (SRTs), the detailed examination of their auditory functions revealed deteriorated processing of temporal parameters [gap detection threshold (GDT), interaural time difference (ITD) detection] which was partially responsible for the altered perception of distorted speech (speech in babble noise, gated speech). An analysis of interactions between peripheral and central auditory abilities, showed a stronger influence of peripheral function than temporal processing ability on speech perception in silence in the elderly with normal cognitive function. However, in a more natural environment mimicked by the addition of background noise, the role of temporal processing increased rapidly