Abstract:

We compare the normal modes of vibration and sound radiation from two Gibson F-type mandolins, one with an elliptical sound hole and one with f-holes. The instruments were constructed by the first author, using carved plates and other parts supplied by the Gibson company. Normal modes of vibration were determined with the help of electronic TV holography. Air cavity modes were determined by imbedding the instruments in sand to immobilize the plates. Normal modes in a mandolin are somewhat akin to those observed in guitars, although the coupling between plates and the enclosed air is weaker in mandolins.