A sound adjustment method includes the following steps: obtaining a sound signal including frequency bands with a corresponding original sound pressure level value; converting the original sound pressure level value of each frequency band into a corresponding loudness level value; adjusting each loudness level value by a preset loudness level value to obtain an adjusted loudness level value of each frequency band; converting each adjusted loudness level value into a corresponding adjusted sound pressure level value; calculating a target sound pressure level value of each frequency band according to the original sound pressure level of each frequency band and each adjusted sound pressure level value; adjusting the original sound pressure level value of each frequency band by each target sound pressure level value to obtain an adjusted sound signal; outputting the adjusted sound signal.