MODAL-ANALYSIS OF ACOUSTIC FIELDS

Modal analysis was primarily conceived for the measurement of mechanical vibrations, although it can also be applied to the study of acoustic fields. On the practical examples of wind instruments such as the flute and bassoon it can be shown that consideration the phase of the acoustic pressure leads not only to a grasping of the most rational of measures, but rather to the capture of other interesting additional information. From a complete knowledge of all the modes in the interior of the body of an instrument it is possible to determine the distribution of acoustic pressure in the partials of a note for which the frequencies do not coincide with the resonances. The craftsmanship of the instrument will provide valuable information concerning the influence of certain structural details on the quality of instruments. Other applications of modal analysis can be well imagined, particularly in architectural acoustics (e.g. the measurement of stationary waves in small rooms), or in the metrology of noise.