How is amplitude changed in an instrument or tuning fork

Amplitude is affected by the energy wave in the instrument. High energy wave means high amplitude and low energy wave means low amplitude.

Explanation:

The amplitude of a periodic variable is a measure of its change over a single period. There are various definitions of amplitude, which are all functions of the magnitude of the differences between the variable's extreme values.

The amount of energy carried by a wave is related to the amplitude of the wave. Amplitude of an instrument is directly affected by the wave of the energy in the instruments. High energy wave means high amplitude and low energy wave means low amplitude in the instrument.