Robust coding of the spectral shape of sound by the auditory system is crucial for accurate speech perception, in particular with vowels. Although recent computational models of the peripheral auditory system suggest which neural information available at the level of the auditory nerve could code for spectral shape (such as formant positions in a vowel), the contribution of the different neural indices available to perception has never been studied systematically. This internship has two aims. The first aim will be to construct psychophysical experiments to quantitatively assess the impact of specific manipulations of vowel signals, informed by model simulations, on timbre perception, and thus to provide information about the neural cues that are effectively exploited in perception. The second aim will be to evaluate the extent to which cochlear synaptopathy, a “hidden” form of hearing loss at the level of the auditory nerve that cannot be detected with an audiogram, affects this coding and could therefore explain differences in perceptual sensitivity to spectral shape modifications across normal-hearing individuals. This internship will take place in the STMS Lab (Sciences et Technologies de la Musique et du Son) at Ircam (Institut de Recherche et Coordination Acoustique/Musique) in Paris.