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Purpose Adults with mild-to-moderate age-related hearing loss typically exhibit issues with speech understanding, but their processing of syntactically complex sentences is not well understood. We test the hypothesis that listeners with hearing loss' difficulties with comprehension and processing of syntactically complex sentences are due to the processing of degraded input interfering with the successful processing of complex sentences. Method We performed a neuroimaging study with a sentence comprehension task, varying sentence complexity (through subject–object order and verb–arguments order) and cognitive demands (presence or absence of a secondary task) within subjects. Groups of older subjects with hearing loss ( n = 20) and age-matched normal-hearing controls ( n = 20) were tested. Results The comprehension data show effects of syntactic complexity and hearing ability, with normal-hearing controls outperforming listeners with hearing loss, seemingly more so on syntactically complex sentences. The secondary task did not influence off-line comprehension. The imaging data show effects of group, sentence complexity, and task, with listeners with hearing loss showing decreased activation in typical speech processing areas, such as the inferior frontal gyrus and superior temporal gyrus. No interactions between group, sentence complexity, and task were found in the neuroimaging data. Conclusions The results suggest that listeners with hearing loss process speech differently from their normal-hearing peers, possibly due to the increased demands of processing degraded auditory input. Increased cognitive demands by means of a secondary visual shape processing task influence neural sentence processing, but no evidence was found that it does so in a different way for listeners with hearing loss and normal-hearing listeners.

Agrammatic speech is characterized by the omission and substitution of grammatical morphemes. Some recent papers suggest that certain patterns of omission and substitution are ruled by linguistic, that is, syntactic processes (e.g., Hagiwara, 1995; Friedmann & Grodzinsky, 1997; Bastiaanse & Van Zonneveld, 1998). In the present paper, the omission pattern of case markers in the spontaneous speech of Dutch and German speakers with agrammatic aphasia is analyzed within the framework of Chomsky's (1986) case theory , which says that every phonetically realized NP must receive (abstract) case. The inflected verb (I) assigns nominative case to the subject in the sentence, and the verb (V) assigns dative and accusative case to the indirect and direct object, respectively. This, in combination with the knowledge that verbs and verb inflections are notoriously difficult for speakers with agrammatism, served as the basis for this study. We hypothesize that, if no case assigner is produced, the noun will receive nominative case by default or the case marking morpheme (i.e., the determiner) will be omitted. This hypothesis has been tested and was supported by the data.