A headphone (100, 200), comprising: an ear-cup housing; and an audio driver (110, 218) disposed at least partially within the ear-cup housing, the audio driver (110, 218) including: a driver housing; a diaphragm suspended from the driver housing; one of a magnet and a coil carried on a back side of the diaphragm; and another of the magnet and the coil carried by the driver housing behind the diaphragm, the magnet and coil magnetically coupled with one another such that electrical current flowing through the coil generates a magnetic force acting on the diaphragm through the magnet or coil carried on the back side of the diaphragm; and a driver aperture extending into the audio driver (110, 218) from an exterior thereof toward the diaphragm; the headphone (100, 200) being characterized in that the headphone (100, 200) further comprises a mass port plug (166, 166') disposed at least partially within the driver aperture, the mass port plug (166, 166') having an acoustic aperture extending through the mass port plug (166, 166') from a first side thereof to an opposing second side thereof, the acoustic aperture configured to cause the audio driver (110, 218) to exhibit a selected detectable sound pressure level profile, and the driver housing comprises a port extending through a surface of the driver housing directly between an acoustical cavity within the driver housing and an exterior of the ear-cup housing without communicating acoustically with a volume of space outside the driver housing and within the ear-cup housing. an ear-cup housing; and an audio driver (110, 218) disposed at least partially within the ear-cup housing, the audio driver (110, 218) including: a driver housing; a diaphragm suspended from the driver housing; one of a magnet and a coil carried on a back side of the diaphragm; and another of the magnet and the coil carried by the driver housing behind the diaphragm, the magnet and coil magnetically coupled with one another such that electrical current flowing through the coil generates a magnetic force acting on the diaphragm through the magnet or coil carried on the back side of the diaphragm; and a driver housing; a diaphragm suspended from the driver housing; one of a magnet and a coil carried on a back side of the diaphragm; and another of the magnet and the coil carried by the driver housing behind the diaphragm, the magnet and coil magnetically coupled with one another such that electrical current flowing through the coil generates a magnetic force acting on the diaphragm through the magnet or coil carried on the back side of the diaphragm; and a driver aperture extending into the audio driver (110, 218) from an exterior thereof toward the diaphragm; the headphone (100, 200) being characterized in that the headphone (100, 200) further comprises a mass port plug (166, 166') disposed at least partially within the driver aperture, the mass port plug (166, 166') having an acoustic aperture extending through the mass port plug (166, 166') from a first side thereof to an opposing second side thereof, the acoustic aperture configured to cause the audio driver (110, 218) to exhibit a selected detectable sound pressure level profile, and the driver housing comprises a port extending through a surface of the driver housing directly between an acoustical cavity within the driver housing and an exterior of the ear-cup housing without communicating acoustically with a volume of space outside the driver housing and within the ear-cup housing.