In-ear active noise reduction earphone
An active noise reduction earphone. The earphone includes structure for positioning and retaining the earphone in the ear of a user without a headband, active noise reduction circuitry including an acoustic driver with a nominal diameter greater than 10 mm oriented so that a line parallel to, or coincident with, an axis of the acoustic driver and that intersects a centerline of the nozzle intersects the centerline of the nozzle at angle θ>±30 degrees. A microphone is positioned adjacent an edge of the acoustic driver. The earphone is configured so that a portion of the acoustic driver is within the concha of a user and another portion of the acoustic driver is outside the concha of the user when the earphone is in position. An opening coupling the nozzle to the environment includes impedance providing structure in the opening.
1. An active noise reduction (ANR) earphone, comprising:
an acoustic driver configured to deliver acoustic energy into a front cavity,
the front cavity including a first volume of space inside the earphone and into which the acoustic driver delivers the acoustic energy, a second volume of space inside the ear canal of a user, and a nozzle section coupling the first and second volumes;
a tip for coupling the earphone to the ear of the user, the tip including at least a portion of the nozzle section coupling the first volume of the front cavity to the second volume of the front cavity; and
active noise reduction circuitry comprising
a feedback microphone acoustically coupled to the first volume of the front cavity, for detecting noise in the front cavity;
feedback circuitry responsive to the feedback microphone for providing a feedback noise cancelling audio signal into the front cavity;
a feed-forward microphone acoustically coupled to ambient space outside the housing;
feed-forward circuitry responsive to the feed-forward microphone for providing a feed-forward noise canceling audio signal into the front cavity; and
wherein the acoustic driver is configured to transduce an output noise canceling audio signal comprising the feedback noise canceling audio signal and the feed-forward noise canceling audio signal into acoustic energy;
wherein the nozzle is oriented and shaped to control the acoustic impedance of the nozzle, such that at least one of the cross-sectional area of the nozzle, the ratio of the nozzle length to the nozzle cross sectional area, or the acoustic mass of the nozzle causes the impedance of the nozzle to be below a threshold that varies over the operating range of the active noise reduction circuitry.
2. The earphone of claim 1 , wherein the nozzle section is formed of a rigid material.
3. The earphone of claim 1 , wherein the nozzle is configured to penetrate at least partially into the opening of the ear canal of a user.
4. The earphone of claim 3 , wherein the ear tip is at least partially formed of a compliant material and covers at least the portion of the nozzle that penetrates into the opening of the ear canal of the user.
5. The earphone of claim 1 , wherein the nozzle comprises a rigid portion and a compliant portion.
6. The earphone of claim 5 , wherein the nozzle comprises a frusto-conically shaped structure for engaging the area of transition between the ear canal and the bowl of the concha and acoustically coupling the ear canal with the nozzle.
7. The earphone of claim 1 , wherein the tip is configured to form a seal near the area of transition between the ear canal and the bowl of the concha.
8. The earphone of claim 1 , wherein the tip includes a frusto-conically-shaped portion formed of a compliant material for acoustically sealing the area of transition between the ear canal and the bowl of the concha.
9. The earphone of claim 7 or 8 , wherein the tip is configured to terminate near the entrance of the ear canal such that it does not substantially penetrate into the ear canal.
10. The earphone of claim 1 , wherein the tip is removable from the housing.
11. The earphone of claim 10 , wherein the tip includes a frusto-conically-shaped portion formed of a compliant material for acoustically sealing the area of transition between the ear canal and the bowl of the concha, and is interchangeable with ear tips having differently-sized frustro-conically-shaped portions.
12. The earphone of claim 10 , wherein the tip includes a leg engaging the outer ear for positioning and retaining the earphone in the ear of a user, and is interchangeable with tips having differently-sized retaining legs.
13. The earphone of claim 1 ,
wherein the acoustic driver is oriented so that a line parallel to, or coincident with, an axis of the acoustic driver intersects a centerline of the nozzle at angle θ>±30 degrees.
14. The earphone of claim 1 ,
wherein the absolute value of the mass impedance |z| of the nozzle section is
8.0
×
10
6
kg
m
4
sec
or less at 1 kHz.
15. The earphone of claim 1 ,
wherein the absolute value of the mass impedance |z| of the nozzle section is
800
×
10
3
kg
m
4
sec
or less at 100 Hz.
16. The earphone of claim 1 ,
wherein the nozzle section has an acoustic mass
1200
kg
m
4
or less, where
M
=
ρ
l
A
,
ρ is the density of air, A is the open cross sectional area of the nozzle section and l is the length of the nozzle section.
17. The earphone of claim 1 , further comprising structure engaging the outer ear for positioning and retaining the earphone in the ear.
18. The earphone of claim 1 , wherein the acoustic driver has a nominal diameter of greater than 10 mm.
19. The earphone of claim 15 , where the acoustic driver has a nominal diameter of greater than 14 mm.
20. The earphone of claim 1 , wherein the earphone is configured so that a portion of the acoustic driver is within the concha of a user and another portion of the acoustic driver is outside the concha of the user when the earphone is in position.
21. The earphone of claim 1 , wherein the feedback microphone is radially positioned intermediate a point at which a diaphragm of the acoustic driver is attached to a voice coil of the acoustic driver and an edge of the diaphragm.
22. The earphone of claim 1 , wherein the feedback microphone is positioned at the intersection of a module supporting the acoustic driver and the nozzle section.
23. The earphone of claim 1 , wherein
the front cavity is coupled to a first sound-radiating surface of the acoustic driver; and the earphone further comprises
a rear cavity coupled to a second sound-radiating surface of the acoustic driver and defining an enclosed acoustic volume, including a port coupling the enclosed acoustic volume to the ambient space around the earphone.
24. An active noise reduction (ANR) earphone, comprising:
an acoustic driver configured to deliver acoustic energy into a front cavity,
the front cavity including a first volume of space inside the earphone and into which the acoustic driver delivers the acoustic energy, a second volume of space inside the ear canal of a user, and a nozzle section coupling the first and second volumes,
wherein the acoustic driver is oriented so that a line parallel to, or coincident with, an axis of the acoustic driver intersects a centerline of the nozzle section at an angle θ>±30 degrees, and
the absolute value of the mass impedance |z| of the nozzle section is
8.0
×
10
6
kg
m
4
sec
or less at 1 kHz;
a tip for coupling the earphone to the ear of the user,
the tip including at least a portion of the nozzle section coupling the first volume of the front cavity to the second volume of the front cavity; and
active noise reduction circuitry comprising
a feedback microphone acoustically coupled to the first volume of the front cavity, for detecting noise in the front cavity;
feedback circuitry responsive to the feedback microphone for providing a feedback noise cancelling audio signal into the front cavity;
a feed-forward microphone acoustically coupled to ambient space outside the housing;
feed-forward circuitry responsive to the feed-forward microphone for providing a feed-forward noise canceling audio signal into the front cavity; and
wherein the acoustic driver is configured to transduce an output noise canceling audio signal comprising the feedback noise canceling audio signal and the feed-forward noise canceling audio signal into acoustic energy.
25. An active noise reduction (ANR) earphone, comprising:
an acoustic driver configured to deliver acoustic energy into a front cavity,
the front cavity including a first volume of space inside the earphone and into which the acoustic driver delivers the acoustic energy, a second volume of space inside the ear canal of a user, and a nozzle section coupling the first and second volumes,
wherein the acoustic driver is oriented so that a line parallel to, or coincident with, an axis of the acoustic driver intersects a centerline of the nozzle section at an angle θ>±30 degrees, and
the absolute value of the mass impedance |z| of the nozzle section is
800
×
10
3
kg
m
4
sec
or less at 100 Hz;
a tip for coupling the earphone to the ear of the user,
the tip including at least a portion of the nozzle section coupling the first volume of the front cavity to the second volume of the front cavity; and
active noise reduction circuitry comprising
a feedback microphone acoustically coupled to the first volume of the front cavity, for detecting noise in the front cavity;
feedback circuitry responsive to the feedback microphone for providing a feedback noise cancelling audio signal into the front cavity;
a feed-forward microphone acoustically coupled to ambient space outside the housing;
feed-forward circuitry responsive to the feed-forward microphone for providing a feed-forward noise canceling audio signal into the front cavity; and
wherein the acoustic driver is configured to transduce an output noise canceling audio signal comprising the feedback noise canceling audio signal and the feed-forward noise canceling audio signal into acoustic energy.
26. An active noise reduction (ANR) earphone, comprising:
an acoustic driver configured to deliver acoustic energy into a front cavity,
the front cavity including a first volume of space inside the earphone and into which the acoustic driver delivers the acoustic energy, a second volume of space inside the ear canal of a user, and a nozzle section coupling the first and second volumes,
wherein the acoustic driver is oriented so that a line parallel to, or coincident with, an axis of the acoustic driver intersects a centerline of the nozzle section at an angle θ>±30 degrees, and
the nozzle section has an acoustic mass M of
1200
kg
m
4
or less, where
M
=
ρ
l
A
,
ρ is the density of air, A is the open cross sectional area of the nozzle section and l is the length of the nozzle section;
a tip for coupling the earphone to the ear of the user,
the tip including at least a portion of the nozzle section coupling the first volume of the front cavity to the second volume of the front cavity; and
active noise reduction circuitry comprising
a feedback microphone acoustically coupled to the first volume of the front cavity, for detecting noise in the front cavity;
feedback circuitry responsive to the feedback microphone for providing a feedback noise cancelling audio signal into the front cavity;
a feed-forward microphone acoustically coupled to ambient space outside the housing;
feed-forward circuitry responsive to the feed-forward microphone for providing a feed-forward noise canceling audio signal into the front cavity; and
wherein the acoustic driver is configured to transduce an output noise canceling audio signal comprising the feedback noise canceling audio signal and the feed-forward noise canceling audio signal into acoustic energy.