An earphone includes a first acoustic chamber having a reactive element and a resistive element in a parallel configuration, a second acoustic chamber separated from the first acoustic chamber by an acoustic transducer and including a unitary port to provide both pressure equalization of the second chamber and equalization of the earphone to a predetermined frequency response, and a housing to support the apparatus from the concha of a wearer's ear and to extend the second acoustic chamber into the ear canal of the wearer's ear.