▁languages . ▁ ▁R ingen ▁earned ▁her ▁Ph . D . ▁in ▁L ingu istics ▁from ▁Indiana ▁University ▁in ▁ 1 9 7 5 , ▁with ▁a ▁dis sert ation ▁entitled ▁" V owel ▁Harm ony : ▁The oret ical ▁Imp lications ." ▁After ▁her ▁Ph D ▁she ▁took ▁up ▁a ▁position ▁at ▁the ▁University ▁of ▁Iowa ▁L ingu istics ▁Department , ▁where ▁she ▁stayed ▁until ▁her ▁ret irement ▁in ▁ 2 0 1 5 . ▁ ▁R ingen ▁was ▁co - editor ▁of ▁the ▁Nord ic ▁Journal ▁of ▁L ingu istics ▁from ▁ 2 0 0 1 – 2 0 1 5 . ▁She ▁served ▁on ▁the ▁Executive ▁Committee ▁of ▁the ▁L ingu istic ▁Society ▁of ▁America ▁from ▁ 2 0 0 8 – 2 0 1 0 . ▁She ▁was ▁a ▁member ▁of ▁the ▁scientific ▁committee ▁of ▁the ▁Manchester ▁Ph on ology ▁Me eting ▁from ▁ 2 0 0 4 ▁to ▁ 2 0 1 4 . ▁ ▁Key ▁publications ▁▁ ▁Hel g ason , ▁P ét ur , ▁and ▁Catherine ▁O . ▁R ingen . ▁ 2 0 0 8 . ▁Vo icing ▁and ▁asp iration ▁in ▁Swedish ▁stops . ▁Journal ▁of ▁Ph on et ics ▁ 3 6 , ▁ 6 0 7 – 6 2 8 . ▁ ▁J essen , ▁Michael ▁and ▁Catherine ▁O . ▁R ingen . ▁ 2 0 0 2 . ▁L ary n ge al ▁features ▁in ▁German . ▁Ph on ology ▁ 1 9 , ▁ 1 8 9 – 2 1