A sound enhancement method is applied to a communication apparatus with an operation processor for increasing speech quality. The sound enhancement method includes the operation processor utilizing a sound receiver of the communication apparatus to acquire an input source, the operation processor applying a first calibration model to the input source for executing communication calibration and simultaneously analyzing the input source to determine whether to establish a second calibration mode, and the operation processor utilizing the second calibration mode to execute the communication calibration when the second calibration mode is established.