APPLICATIONS OF OPERATIONAL MODAL ANALYSIS TO THE ACOUSTIC OF MUSICAL INSTRUMENTS: SNARE DRUM AND CELLO

摘要

Sound waves are formed when the vibrations of musical instruments cause the medium (air) to vibrate. Although musical instruments are apparently something simple, they are actually complex systems where coupled motion between the air and the "structure" has a great influence in the acoustic of the instrument. This is for example the case of bowed string instruments (violin or cello) where the top plate, the back plate and the enclosed air determine the resonance chamber where the vibration of the air is produced. In other cases, like drums, the interaction can be less relevant but not negligible. However, other parameters like the pre-stress applied to the membranes (drumhead) are more significant. In this work, a vibration analysis of the top plate of a cello and the drumhead of a snare drum were carried out. Operational modal analysis (OMA) was applied to identify the modal parameters which are then used to improve the understanding of the acoustic properties of these musical instruments.