Abstract: A sealed headphone having an improved sound pressure versus frequency response characteristic is disclosed. The sealed headphone comprises a mounting plate having coupling apertures, an electro-acoustic transducer attached to one side of the mounting plate and a casing covering the transducer. A space defined by the rear side of the transducer and the casing communicates via the coupling apertures with another spaced formed on the opposite side of the mounting plate so as to form an acousto-mechanical resonance circuit within the headphone. By raising the parallel resonance frequency of the resonance circuit, a higher reproduced frequency limit of the headphone is achieved.