The physics of the viola caipira

Presenter: Dr. Guilherme Paiva

Live transmission @ário

The viola caipira is a Brazilian guitar widely used in popular music and has been little studied in musical acoustics. Generally, it consists of ten metallic strings arranged in five pairs, tuned in unison or octave. In this seminar, the author presents some results obtained in his thesis research, which focused on the analysis and synthesis of musical sounds produced by the viola caipira.

The analysis of the motions of plucked strings using a high speed camera shows the existence of sympathetic vibrations, which results in a sound halo, constituting an important perceptive feature. These measurements also reveal the existence of shocks between strings, which lead to very clearly audible consequences. The modal analysis of the body vibrations, carried out by a scanning laser vibrometer and an automatic impact hammer reveals some differences and similarities with the classical guitar.

A physical modelling, based on a modal approach, is carried out for sound synthesis purposes. It takes into account the strings motions with two orthogonal polarizations, the couplings with the body and the collisions between strings. This model is hybrid since it combines an analytical approach to describe the vibrations of strings and experimental data describing the body. Simulations in the time domain finally reveal the main characteristics of the viola caipira.

(video presentation in portuguese)

When: June 16th, 2020