A method is presented which semi-automatically extracts the fundamental frequency and displays as continuous signals vibrato rate, vibrato extent and sound level. The method is tested on specially made recordings of violin music with piano accompaniment, using a small microphone mounted directly on the violin. The fundamental frequency was successfully extracted by means of a waveform correlation program. Likewise, vibrato rate and extent were extracted separately for each tone from the fundamental frequency signal after elimination of its DC component. The results seem promising, offering the opportunity of visual examination and measurement of changes in vibrato characteristics during performances of entire pieces of music.