The study hypothesis is that a link might exist between hearing deficits and olfactory deficits in these children due to viral lesions on the two sensory systems. Thus early exploration of olfaction might allow early detection of starting deterioration of hearing or predict the occurrence of deafness. Moreover, this exploration is easy, non invasive, fast to set up and adapted to very young children. No study has hitherto assessed the impact of congenital CMV infection on olfaction.