[2]: 201 She was a member of the Danish resistance movement fighting against the German occupation of Denmark.
[2]: 198 She specialized in linguistics and her thesis treated "the importance of dialect geography for the perception of sound changes".
[2]: 199 From 1933 she became a member of the Linguistic Circle of Copenhagen which evolved around Louis Hjelmslev and his theory of glossematics.
Tired of the theoretical discussions of Hjelmslev's circle, she took up research in the field of phonetics in which she became an international figure, publishing widely used text books about general phonetics and phonological theory.
[2]: 200 During the German occupation of Denmark from 1940 to 1945, she worked in the resistance group of Professor Carsten Høeg and under great risk helped him assemble a list of Danish nazis to be prosecuted after the liberation.