Earphone

A noise cancelling system, comprising:

• noise cancellation circuitry;
• and
• an earphone, the earphone comprising:
• an earphone housing;
• a speaker mounted within the earphone housing,
• a first microphone, positioned to detect ambient noise approaching the ear of a wearer of the earphone, and
• a cable inlet, containing a cable that includes a wire connected to the speaker and a wire connected to the first microphone,
• wherein the cable inlet has projections on an inner surface thereof, such that the cable is in partial contact with said projections on the inner surface of the cable inlet over a substantial portion of the length of the cable inlet, while a rear volume of the speaker is vented through the cable inlet,
• wherein the noise cancellation circuitry is adapted to receive an ambient noise signal from the first microphone, and to generate a noise cancellation signal in response thereto.

A noise cancelling system, comprising:

• noise cancellation circuitry;
• and
• an earphone, the earphone comprising:
• an earphone housing;
• a speaker mounted within the earphone housing,
• a first microphone, positioned to detect ambient noise approaching the ear of a wearer of the earphone,
• a second microphone, positioned to detect noise entering the ear of a wearer of the earphone, and
• a cable inlet, containing a cable that includes a wire connected to the speaker, a wire connected to the first microphone, and a wire connected to the second microphone,
• wherein the cable inlet has projections on an inner surface thereof, such that the cable is in partial contact with said projections on the inner surface of the cable inlet over a substantial portion of the length of the cable inlet, while a rear volume of the speaker is vented through the cable inlet,
• wherein the noise cancellation circuitry is adapted to receive an ambient noise signal from the first microphone, and to generate a noise cancellation signal in response thereto, and
• wherein the noise cancellation circuitry is adapted to receive an error signal from the second microphone, and to control an amount of gain applied to the ambient noise signal to generate the noise cancellation signal in response to the error signal.

An earphone, comprising:

• an earphone housing;
• and
• a speaker mounted within the earphone housing,
• wherein the earphone comprises a cable inlet, containing a cable that includes a wire connected to the speaker, and
• wherein the cable and the cable inlet have different cross-sectional shapes, such that the cable is in contact with the inner surface of the cable inlet at at least two points on their cross-section over a substantial portion of their length, while a rear volume of the speaker is vented through the cable inlet.