The AgeHear project is firmly based on the perspective of access to speech comprehension for the elderly suffering of Age-related hearing loss in a dual framework of both basic and clinical research. Hearing loss is a growing challenge in our modern society, and has a significant socio-economic impact, particularly with regard to the ageing population. Age-related hearing loss (ARHL or presbycusis) is present in about two thirds of the elderly, causing serious communication difficulties and leading to social isolation and depression. This difficulty in communicating is worsened by a cognitive decline related to the listening effort which depletes the person's cognitive resources. These demographic and clinical issues are at the heart of AgeHear project, which focuses on understanding the mechanisms of rehabilitation of presbycusis subjects with hearing aids (HAs). Thanks to technological advances, hearing aids enable the elderly to have access to oral communication and to return to an enriched social life. From a fundamental point of view, based on a multidisciplinary approach combining psychophysics, neuropsychology and brain imaging, AgeHear will seek to understand the mechanisms of brain plasticity involved in the rehabilitation of speech in the noise of the presbycusis subject and the links with a reduction in cognitive effort. From a clinical point of view, AgeHear will make it possible to use this experimental and theoretical understanding to support and guide the implementation of rehabilitation strategies. The central theme of AgeHear thus concerns the mechanisms of spatial hearing and neurocognitive compensation and their impact on the recovery of speech comprehension by hearing aids. The originality of AgeHear is both technological and theoretical. Conceptually, AgeHear proposes to study the mechanisms of spatial hearing restoration in a natural ecological context including dynamic and multisensory components. The impact and strategies supporting the rehabilitation of speech understanding in noise will be evaluated using a 3D virtual system (HTC ViveTM) allowing the patient to be immersed in a controlled vivid visuo-auditory environment. At the heart of AgeHear is the strong hypothesis that the success of rehabilitation of the presbycusis subject depends on his potential of brain plasticity. Based on a longitudinal approach, we will search for neural markers through PET scan brain imaging which would be predictive of the level of recovery by HAs and could consequently guide individual rehabilitation strategies. PET imaging will also allow us to determine whether spatial hearing and speech in noise comprehension share the same cognitive resources. This aspect will be reinforced by analyzing the links between hearing loss and its recovery with deficits in executive functions. Thus, AgeHear is a definitely a multidisciplinary and translational project that brings together two laboratories with expertise in brain imaging and psychophysics of deafness associated with an ENT service in addition to the participation of an industrial partner specialized in hearing aids. This consortium will enable a complementary approach, from psychophysics to clinical neurosciences, with a single common objective of a better understanding of the mechanisms of rehabilitation of presbycusis in its perceptive and cognitive aspects in order to optimize the rehabilitation of the elderly, thus promoting their social reintegration.