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In page Tera de Marez Oyens:

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In the 1960s she became interested in electronic music, and studied with Gottfried Michael Koenig at the Institute of Sonology in Utrecht (Metzelaar n.d.) harv error: no target: CITEREFMetzelaarn.d. (help). Sound and Silence (1971) and Mixed Feelings (1973) are pieces of electronic music she composed, and Pente Sjawoe is an example of a work in which the tone poem plays an important role.[citation needed]