A headphone comprising an audio unit carried by a support structure of the headphone that is adapted to sit on a head of a user, the audio unit being held off an ear of the user so that the user can hear conversations and other environmental sounds, the audio unit comprising: a first acoustic driver carried by the support structure such that the first acoustic driver is located off of the ear of the user, wherein the first acoustic driver has front and rear sides; wherein the first acoustic driver is enclosed by a housing defining: a front chamber acoustically coupled to the front side of the first acoustic driver; and a rear chamber acoustically coupled to the rear side of the first acoustic driver; wherein the housing comprises a first port that is acoustically coupled to the front chamber and a second port that is acoustically coupled to the rear chamber, the first port being arranged to direct sound toward the ear of the user, the second port being farther from the ear of the user than is the first port and being directed away from the ear of the user, the second port being further arranged for radiating 180 degrees out of phase with the sound from the first port so as to cause far field sound cancellation, wherein the audio unit is arranged so that, in use, the first port directs sound downwards and the second port directs sound upwards, and wherein the first port has an acoustic resistance material proximate to the first port and wherein the second port has an acoustic resistance material proximate to the second port. a first acoustic driver carried by the support structure such that the first acoustic driver is located off of the ear of the user, wherein the first acoustic driver has front and rear sides; wherein the first acoustic driver is enclosed by a housing defining: a front chamber acoustically coupled to the front side of the first acoustic driver; and a rear chamber acoustically coupled to the rear side of the first acoustic driver; wherein the housing comprises a first port that is acoustically coupled to the front chamber and a second port that is acoustically coupled to the rear chamber, the first port being arranged to direct sound toward the ear of the user, the second port being farther from the ear of the user than is the first port and being directed away from the ear of the user, the second port being further arranged for radiating 180 degrees out of phase with the sound from the first port so as to cause far field sound cancellation, wherein the audio unit is arranged so that, in use, the first port directs sound downwards and the second port directs sound upwards, and wherein the first port has an acoustic resistance material proximate to the first port and wherein the second port has an acoustic resistance material proximate to the second port. a front chamber acoustically coupled to the front side of the first acoustic driver; and a rear chamber acoustically coupled to the rear side of the first acoustic driver; wherein the housing comprises a first port that is acoustically coupled to the front chamber and a second port that is acoustically coupled to the rear chamber, the first port being arranged to direct sound toward the ear of the user, the second port being farther from the ear of the user than is the first port and being directed away from the ear of the user, the second port being further arranged for radiating 180 degrees out of phase with the sound from the first port so as to cause far field sound cancellation, wherein the audio unit is arranged so that, in use, the first port directs sound downwards and the second port directs sound upwards, and wherein the first port has an acoustic resistance material proximate to the first port and wherein the second port has an acoustic resistance material proximate to the second port.