[1] Childrens Hosp Pittsburgh, Dept Pediat, Pittsburgh, PA 15213 USA
[2] Childrens Hosp Pittsburgh, Dept Audiol & Commun Disorders, Pittsburgh, PA 15213 USA
[3] Univ Pittsburgh, Dept Pediat, Sch Med, Pittsburgh, PA 15260 USA
[4] Univ Pittsburgh, Dept Family Med & Clin Epidemiol, Sch Med, Pittsburgh, PA USA
[5] Univ Pittsburgh, Dept Communicat Sci & Disorders, Sch Med, Pittsburgh, PA USA
[6] Univ Pittsburgh, Grad Sch Publ Hlth, Dept Biostat, Pittsburgh, PA 15261 USA