Earphone having a controlled acoustic leak port

An earphone comprising:

• an earphone housing having a housing wall comprising a first portion, a second portion, and a third portion that are joined together to enclose a driver, the driver having a front face that outputs sound waves and a back face opposite the front face, the first portion and the second portion define a first chamber coupled to the front face of the driver, and the third portion define a second chamber coupled to the back face of the driver,
• a primary output opening to output sound from the front face of the driver into an ear is formed through the first portion,
• a secondary output opening that vents the ear to a surrounding environment is formed through the second portion, the secondary output opening and the primary output opening face different directions, and
• a first port is formed through the housing wall defining the second chamber.