CHAOS (Cultural Heritage Archive Open System) provides streaming access to more than 500,000 broadcasts by the Danish Broadcast Corporation from 1931 and onwards. The archive is part of the LARM project with the purpose of enabling researchers to search, annotate, and interact with recordings. To optimally support the researchers a user-centred approach was taken to develop the platform and related metadata scheme. Based on the requirements a three level metadata scheme was developed: (1) core archival metadata, (2) LARM metadata, and (3) project-specific metadata. The paper analyses how researchers apply the metadata scheme in their research work. The study consists of two studies, a) a qualitative study of subjects and vocabulary of the applied metadata and annotations, and 5 semi-structured interviews about goals for tagging. The findings clearly show that the primary role of LARM.fm is to provide access to broadcasts and provide tools to segment and manage concrete segments of radio broadcasts. Although the assigned metadata are project-specific, they serve as invaluable access points for fellow researchers due to their factual and neutral nature. The researchers particularly stress LARM.fm’s strength in providing streaming access to a large, shared corpus of broadcasts.