Advances in acoustics instruments measurements and system design

This paper presents the progress of sine-sweep based measurements to gather impulse responses of musical instruments, in particular acoustic guitars. In the attempt of quantifying the accuracy limit of the methodology a fully working instrument has been re-worked, and all phases of the process have been measured before and after each modification step. This provided useful data to perform a sensitivity analysis of this technique, and also showed the similarity between tuning a soundboard and tuning a dipole loudspeaker system based on a resonating plate and an exciter. The collected data proved that the measurement method is capable of capturing the influence of the varnish being applied or removed from the soundboard, the presence or absence of structural reinforcing struts (braces), and the presence or absence of further weight reduction applied to the braces of the soundboard. The findings suggest this approach is mature and ready to be used in combination with FEM simulations, computer aided machining, and additional manufacturing in order to achieve a desired frequency response for acoustic soundboards or panel loudspeakers. Furthermore, the responses collected with this method can be used for auralisation and creative purposes, enabling the community of guitar makers and players to progress in the difficult task of correlating quantitative data with players’ preference.