A compatible circuit and method for 4- and 5-pole earphones and a portable device are disclosed. The compatible circuit and method alter the path of audio signals, using switches, according to control signals, so that the 4-pole earphone can be used in a portable device designed primarily for a 5-pole earphone. The apparatus and method include determining the type of earphone, altering the audio signal path according to the type of earphone, and transmitting the audio signal to the earphone.