Speech perception after cochlear implantation over a 4-year time period. - Oh,S.H.; Kim,C.S.; Kang,E.J.; Lee,D.S.; Lee,H.J.; Chang,S.O.; Ahn,S.H.; Hwang,C.H.; Park,H.J.; Koo,J.W. (Acta Otolaryngol, 2003)