A sound adjustment method is disclosed. The sound adjustment method includes the following the steps: receiving a sound adjustment command; receiving a right channel sound signal and a left channel sound signal; selecting a corresponding adjustment mode according to the sound adjustment command and processing the right channel sound signal and the left channel sound signal based on the adjustment mode to generate a right channel first sound signal and a left channel first sound signal, wherein different adjustment modes have different intensity adjustment levels; shifting the frequency of the right channel first sound signal by X Hz to generate a right channel second sound signal and shifting the frequency of the left channel first sound signal by Y Hz to generate a left channel second sound signal, wherein 0.5≤|X−Y|≤100; outputting the right channel second sound signal and the left channel second sound signal.