[1] Dept. of Speech Pathol. and Audiol., University of Iowa, Iowa City, IA 52242, United States
[2] Dept. Otolaryngol. Hd./Neck Surg., University of Iowa, Iowa City, IA 52242, United States
[3] Dept. of Communicative Disorder, University of Wisconsin-Madison, Madison, WI 53706, United States