This thesis is concerned with relating the structural properties of the classical guitar to the sound and ‘playability’ of the instrument. Holographic techniques were used to investigate the effects of different strutting arrangements on the first four modes of the soundboard, via the use of a specially designed experimental rig. The small changes in the distribution of displacement over the soundboard for each mode were found to have important consequences for the way in which a given mode might couple to the string. Small shifts in the nodal lines of some modes were found to change the effective mass of the body modes at the bridge dramatically, which will in turn affect how easily these modes will be driven by the string. Subtle changes in mode shape were also found to affect the body mode characteristics, and therefore the response of the instrument.