An electronic percussion instrument, electronic musical instrument, information processing device, and information processing method are provided. The electronic musical instrument includes a control device that performs processing in which an envelope indicating a change in a reference value over time for determining whether vibration of the second playing operation element is self-induced vibration or excited vibration entailed by vibration of the first playing operation element is generated based on a waveform indicating vibration of the first playing operation element, and processing in which information on the basis of excited vibration of the second playing operation element is prevented from being included in information indicating operation of the second playing operation element using the reference value indicated by the envelope.