An equalization method using equal loudness curve, and a sound output apparatus using the same are disclosed. An audio signal is equalized using a standard loudness curve so as to increase a loudness of an audio signal. A sound quality can be significantly enhanced with the enhancement of a sound cleanness and quality when being adapted to a communication apparatus such as a telephone terminal, a transmitter or a repeater. When it is adapted to an audio apparatus such as a MP3, a common audio system, a car audio system, etc., it is possible to enhance a sound cleanness and quality, and a hearing ability. It can be used as a hearing aid.