An acoustic coupling plate extends from the bridge or vibrato to the neck of the instrument. It acoustically couples the strings, the neck, the instrument body, and either a bridge or a vibrato to alter the acoustic attenuation of the instrument and to reduce the amount of multipath distortion. When a different tonality is desired, this acoustic coupling plate can be divide into two plates and shaped to produce a desirable dampening versus frequency curve. One of these plates acoustically couples the instrument body to the bridge/vibrato and the second plate acoustically couples the neck to the instrument body. A vibrato assembly for stringed instruments makes slight and rapid changes in the pitch of the tone produced by stringed instrument. Previously known vibrato assemblies use knife-edge hinges or rolling ball bearings to produce these variations. The vibrato assemblies described herein use flexure bearings to produce variations in the tension of the strings and thereby the pitch of the tones. These flexure bearing vibrato assemblies have the advantages of high strength, zero operational noise and rumble, and virtually zero friction and hysteresis. Additionally, flexure bearing vibrato assemblies provide a robust path between the instrument and the strings resulting in improved tonal quality, range, and sustain.