This study aims to investigate the underlying mechanisms of speech-in-noise difficulties in patients with normal conventional pure-tone and speech audiometry. Participants presenting with complaints of impaired speech understanding in noisy environments will undergo a comprehensive audiological assessment, including extended high-frequency audiometry, electrocochleography (EcoG), distortion product otoacoustic emissions (DPOAEs), auditory brainstem responses (ABR), and central auditory processing evaluation. The study seeks to identify cochlear, neural, and central auditory abnormalities that may contribute to hidden hearing loss and improve its clinical characterization.