Violin intonation problems caused by body resonances
Norman C. Pickering · The Journal of the Acoustical Society of America · 1982
Strong mechanical resonances in the body of a violin, coupled to the strings through the bridge, cause a shift in the actual frequency of the string which can be 30 cents or more away from the frequency which should exist at a given stopped length. Apparatus has been constructed which permits the detuning effect to be measured. It consists of means for exciting an electrically conducting violin string by the Lorenz force while precisely changing string length with a nylon roller moved along the fingerboard under control of an accurate leadscrew. String amplitude is measured by an optical sensor in the pole-pieces of the magnetic circuit. Results are shown for several instruments of differing characteristics.