The Action of the Cello at the Wolf Tone

Detailed observations of the spectral content of the wolf tone show that the non-linear action of the bow-string contact is important in its production. Input mechanical admittance measurements, and interference holographic techniques confirm that the wolf tone is caused because of coupling between the string and the first mode of vibration of the top plate. Input reactance is calculated, and in the region of the wolf, passes through zero three times confirming the treatment of this defect in the cello on the basis of the analogous circuit for the instrument. Other measurements support the introduction of a criterion to determine when an instrument of the violin family will wolf.