The recordings were made in the municipality of Boarnsterhim in central Fryslân (see Figure  1), because the inhabitants-more than other Frisiansadvocated the monolinguistic use of Frisian (Feitsma 1989  In 1990, the population consisted of 17,710 people and slightly increased every year.
of another division boundary alteration in 2014, Boarnsterhim was again divided and combined with four other municipalities.