An earphone has a housing, with a speaker mounted within the housing. A cable inlet contains a cable that includes a wire connected to the speaker. 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 over a substantial portion of their length, while a rear volume of the speaker is vented through the cable inlet. This ensures that the cross-sectional area through which the rear volume is vented through the cable inlet remains relatively constant. The earphone may further comprise a microphone, positioned to detect ambient noise approaching the ear of a wearer of the earphone, and the cable may then further include a wire connected to the microphone.
1. An earphone, comprising:
an earphone housing; and
a speaker mounted within the earphone housing;
wherein the earphone comprises a cable inlet, comprising a cable that includes a wire connected to the speaker; and
wherein the cable inlet has projections on an inner surface thereof, such that only a part of a cross-section of the cable is in 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.
2. An earphone as claimed in claim 1 , wherein the projections have rectangular cross-sections.
3. An earphone as claimed in claim 1 , wherein the projections have domed shapes.
4. An earphone as claimed in claim 1 , wherein the projections have triangular cross-sections.
5. An earphone as claimed in claim 1 , wherein the projections are provided in multiple lines extending along a length of the cable inlet.
6. An earphone as claimed in claim 5 , wherein there are from 2-8 lines of projections.
7. An earphone as claimed in claim 1 , wherein there is a maximum of 1 or 2 projections at each longitudinal position along the length of the cable inlet.
8. An earphone as claimed in claim 7 , wherein there is a maximum of 1 projection at each longitudinal position along the length of the cable inlet.
9. An earphone as claimed in claim 7 , wherein there are gaps between the longitudinal positions of the projections.
10. An earphone as claimed in claim 1 , further comprising:
a first microphone, positioned to detect ambient noise approaching the ear of a wearer of the earphone, wherein the cable further includes a wire connected to the first microphone.
11. An earphone as claimed in claim 10 , wherein the first microphone is located in a chamber within the housing, said chamber being isolated from the rear volume of the speaker and having at least one hole to the exterior of the earphone.
12. An earphone as claimed in claim 1 , further comprising:
a second microphone, positioned to detect noise entering the ear of a wearer of the earphone, wherein the cable further includes a wire connected to the second microphone.
13. An earphone as claimed in claim 1 , wherein the second microphone is positioned in front of the speaker.
14. An earphone as claimed in claim 1 , having a hole in the housing, such that the rear volume of the speaker is additionally vented through the hole.
15. An earphone as claimed in claim 1 , wherein the cable and the cable inlet have cross-sectional shapes and sizes such that the cable is in contact with the inner surface of the cable inlet at at least three points on its cross-section.
16. 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, comprising 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 only a part of a cross-section of the cable is in 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; and
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.
17. 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, comprising 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 only a part of a cross-section of the cable is in 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; and
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.
18. An earphone, comprising:
an earphone housing; and
a speaker mounted within the earphone housing;
wherein the earphone comprises a cable inlet comprising 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 only a part of a cross-section of 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.
19. An earphone as claimed in claim 18 , further comprising:
a first microphone, positioned to detect ambient noise approaching the ear of a wearer of the earphone, wherein the cable further includes a wire connected to the first microphone.
20. An earphone as claimed in claim 19 , wherein the first microphone is located in a chamber within the housing, said chamber being isolated from the rear volume of the speaker and having at least one hole to the exterior of the earphone.
21. An earphone as claimed in claim 18 , further comprising:
a second microphone, positioned to detect noise entering the ear of a wearer of the earphone, wherein the cable further includes a wire connected to the second microphone.
22. An earphone as claimed in claim 21 , wherein the second microphone is positioned in front of the speaker.
23. An earphone as claimed in claim 18 , having a hole in the housing, such that the rear volume of the speaker is additionally vented through the hole.
24. An earphone as claimed in claim 18 , wherein the cable has a circular cross-section and the cable inlet has a generally circular internal cross-section, with a plurality of ribs protruding from an inner surface thereof, along at least a part of said inner surface.
25. An earphone as claimed in claim 24 , wherein said plurality of ribs protrude from the inner surface thereof along at least 50% of the length of said inner surface.
26. An earphone as claimed in claim 25 , wherein said plurality of ribs extend beyond an inner end of the cable inlet, into the rear volume of the speaker.
27. An earphone as claimed in claim 18 , wherein the cable inlet is in the form of a tube, having a length of at least 10 mm.