Martin Meyer is launching a new SNSF research project about Processing Language and Cognition in Chronic Subjective Tinnitus grant institution on 01.01.2024. Subjective tinnitus is the notion of a percept of chronic high-pitched noise without any objective external sound source.
Presently, it is undisputed that tinnitus must not be considered as a sole dysfunction of the outer or inner ear but rather as a maladaptation of the brain following hearing loss and reorganization of the auditory system. Many (but not all) individuals who suffer chronic subjective tinnitus (TSI) often complain about diffi culties comprehending spoken language, particularly in everyday spoken conversation. In many of these cases the standard threshold audiometry is not indicative of remarkable or severe hearing loss, so other factors may account for the deficient comprehension. Presently, the question of which factors can be considered decisive is difficult to answer because there is a substantial lack of comprehensive studies and hence systematic knowledge about the causality of impaired speech comprehension in TSI. First, only parsimonious literature has investigated the neurophysiological side of this phenomenon, because studies have only looked at the TSI’s behavioral performance in speech-in-noise (SiN) tests. Second, the particular role cognitive skills may play in spoken language comprehension in TSI has yet not been fully investigated. In particular, with respect to the tinnitus brain in which executive functions (EF) have so far been observed to be altered, literally nothing is known about the interplay between spoken language and cognitive functions. Third, there is still uncertainty about the degree of damage tinnitus means for elementary auditory processing, namely the computation of acoustic cues that complex tones and speech sounds are made up of. Fourth, concurrent reports of TSI point to increased difficulties in following spoken conversations (with even more than one speaker) the longer the communicative situation lasts. However, exhaustion and fatigue have so far also not been systematically tested. Fifth, previous studies lack real-life adverse listening conditions when investigating communicative situations. Hence, the proposed project aims to systematically investigate the causality of TSI complaints about difficulties in speech comprehension and their associations with prime perceptual and psychological tinnitus indicators (duration, pitch, distress, coping) as well as comprehensive audiological and cognitive measurements. To minimze heterogeneity, we exclude older people and TSI with noticeable hearing loss from participation. Thus, we are able to investigate more precisely the relationship between auditory and spoken language comprehension and individual cognitive, audiological, and tinnitus-relevant characteristics. We will record audiological and behavioral (psychometrics, cognitive screening) data from a sample of TSI (n=54) and a control group (n=54). Furthermore, the participants will undergo three neurophysiological paradigms investigating auditory, cognitive, and speech functions at different levels, which gives us several options for EEG data analysis (power analysis, event-related brain potentials, phase locking, and coherence analyses). In particular, speech comprehension during spoken conversation in various listening situations will be investigated. Everyday changes in listening situations (speakers’ velocity, number, sex, loudness, and position) will be manipulated to determine which factors account for the reported constraints in everyday communication. Unlike previous studies, we will test spoken comprehension in a full fledged virtual auditory environment where the listening situations are physically modeled in a digital 3D audio environment.
To overcome previous studies that only have looked at distinct aspects of the complex problem in isolation, we will be able to systematically address the question of whether and to what extent audiological, cognitive, situational, and other tinnitus- related characteristics account for the reported and observed speech comprehension difficulties in young and middle-aged adults (age range 23-59) with chronic subjective tinnitus who do not suffer from age-related impediments like moderate or severe hearing loss, brain atrophy, and age-related cognitive decline.