US Patent 9301041 Headphone device

A headphone comprises a speaker. The rear volume of the speaker is coupled to a mixing volume, the front volume of the speaker is coupled to the mixing volume, and the mixing volume is coupled to the exterior. The acoustic impedances resulting from the rear volume, the front volume, the mixing volume, and the passages between them can be adjusted, in order to achieve the desired sound egress properties. Acoustic damping material can be included in the various leakage paths in order to achieve the desired properties, depending on the type of speaker to be used, the acoustic design of the headphone, the mechanical properties of the headphone body, and the desired frequency response characteristics of the headphone.