The function of the violin and the guitar are being investigated. Plate vibrations are recorded by hologram interferometry in cooperation with the Institute of Optical Research, KTH, and a qualitative understanding of eigenmodes and their excitation have been obtained. Properties of the enclosed air volume have been investigated by means of the STL‐Ionophone, which has proved that higher air volume resonances can be used as sound radiators. Played scales recorded in reverberation chamber are analyzed by long‐time‐average‐spectra (LTAS). Such analysis has proved that different instruments may be separated by LTAS. Work is in progress trying to correlate LTAS with function and tonal qualities. Listening tests have been started in cooperation with A. Gabrielsson (Department of Psychology, University of Uppsala). Findings from the present investigations will be reported on. [Work supported by the Swedish Natural Science Research Council and the Swedish Humanistic Research Council.]