A method of controlling sound signals for mixing a backing sound and a guitar sound. The method includes configuring a user terminal to: receive a first input instruction selected from a plurality of available input instructions, where the plurality of available input instructions include a first instruction to transmit a signal of the backing sound; to provide the signal of the backing sound to a wireless communication device in response to the first input instruction being the first instruction to transmit the signal of the backing sound; and to control the wireless communication device to convert the signal of the backing sound to a first wireless signal and transmit the first wireless signal to a sound output device for mixing the signal of the backing sound and a signal of the guitar sound provided from the sound output device.