An earphone comprising: an acoustic driver; a housing containing the acoustic driver; and an ear interface comprising: a body portion that fits beneath the tragus and anti-tragus and has a surface that rests against the concha of a user's ear when worn by the user, an outlet with an oval cross-section, the outlet extending from the body portion and being dimensioned and arranged to fit inside the user's ear canal entrance and to seal the user's ear canal with minimal pressure when worn by the user so that the outlet is not relied upon to provide retention of the earphone in the ear, the outlet providing a passageway for conducting acoustic energy from the acoustic driver to the user's ear canal, and a positioning and retaining structure extending from the body portion and terminating at an extremity, wherein the positioning and retaining structure is arranged for contacting the antihelix of the user's ear along a length of the positioning and retaining structure when the ear interface is fit into the user's ear, and the extremity of the positioning and retaining structure contacts the base of the helix of the user's ear. an acoustic driver; a housing containing the acoustic driver; and an ear interface comprising: a body portion that fits beneath the tragus and anti-tragus and has a surface that rests against the concha of a user's ear when worn by the user, an outlet with an oval cross-section, the outlet extending from the body portion and being dimensioned and arranged to fit inside the user's ear canal entrance and to seal the user's ear canal with minimal pressure when worn by the user so that the outlet is not relied upon to provide retention of the earphone in the ear, the outlet providing a passageway for conducting acoustic energy from the acoustic driver to the user's ear canal, and a positioning and retaining structure extending from the body portion and terminating at an extremity, wherein the positioning and retaining structure is arranged for contacting the antihelix of the user's ear along a length of the positioning and retaining structure when the ear interface is fit into the user's ear, and the extremity of the positioning and retaining structure contacts the base of the helix of the user's ear. a body portion that fits beneath the tragus and anti-tragus and has a surface that rests against the concha of a user's ear when worn by the user, an outlet with an oval cross-section, the outlet extending from the body portion and being dimensioned and arranged to fit inside the user's ear canal entrance and to seal the user's ear canal with minimal pressure when worn by the user so that the outlet is not relied upon to provide retention of the earphone in the ear, the outlet providing a passageway for conducting acoustic energy from the acoustic driver to the user's ear canal, and a positioning and retaining structure extending from the body portion and terminating at an extremity, wherein the positioning and retaining structure is arranged for contacting the antihelix of the user's ear along a length of the positioning and retaining structure when the ear interface is fit into the user's ear, and the extremity of the positioning and retaining structure contacts the base of the helix of the user's ear.