His core expertise is phonology – particularly interactions of metrical structure, (intonational) tone, and segmental structure – and its interfaces with phonetics and morphology, from both a synchronic and a diachronic typological perspective. His current primary focus is on so-called tone accent languages that combine word stress and tonal distinctions (such as Franconian, Lithuanian, or Swedish). In his research, he combines elements from historical linguistics, phonetics, psycholinguistics, and dialectology with phonological theory, often based on original fieldwork.