(12) United States Patent
`Sapiejewski
`
`USOO6683965B1
`(10) Patent No.:
`US 6,683,965 B1
`(45) Date of Patent:
`Jan. 27, 2004
`
`(54) IN-THE-EAR NOISE REDUCTION
`HEADPHONES
`
`(75) Inventor: Roman Sapiejewski, Boston, MA (US)
`
`(*) Notice:
`
`(73) ASSignee: his Corporation, Framingham, MA
`(US)
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 1592 days.
`
`(21) Appl. No.: 08/546,050
`(22) Filed:
`Oct. 20, 1995
`(51) Int. Cl." ................................................ H04R 25/00
`(52) U.S. Cl. ...
`... 381/380: 381/370, 38.1/371
`381/382
`(58) Field of Search ........................... 381/25, 68, 68.6,
`381/71, 72, 74, 94, 183, 187, 309, 322,
`327, 328, 71.6, 380, 382, 370, 94.1; 181/129,
`135; 73/585
`
`56
`(56)
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`6/1969 Giller ........................ 381/68.6
`3,448,224. A
`3/1972 Korn
`3,647,969 A
`3,890.474. A 6/1975 Glicksberg
`4,055,233 A 10/1977 Huntress ..................... 181/135
`4,089,332 A 5/1978 Rose .......................... 128/152
`
`
`
`4,395,588 A 7/1983 Franssen et al.
`4,455,675 A 6/1984 Bose et al. ................... 381/74
`4,622,440 A 11/1986 Slavin .........
`... 381/68.1
`4,677,676 A 6/1987 Eriksson ...................... 381/71
`4,870,688 A 9/1989 Voroba et al. ................ 381/68
`4,985,925 A
`1/1991 Langberg et al. ............. 381/72
`5,134,655 A
`7/1992 Jenssen ...................... 381/183
`5,208,868 A * 5/1993 Sapiejewski ................. 381/74
`5,305,387 A 4/1994 Sapiejewski ................. 381/71
`FOREIGN PATENT DOCUMENTS
`3210O34
`9/1982 ................. 381/187
`DE
`2604551
`4/1986
`FR
`2172769
`9/1986
`GB
`* cited by examiner
`Primary Examiner-Huyen Le
`(74) Attorney, Agent, or Firm-Fish & Richardson P.C.
`(57)
`ABSTRACT
`-
`0
`An in-the-ear earphone which is placed on a user's ear
`including a cushion and a shell body defining an internal
`cavity. The shell body has an extended portion shaped and
`sized to fit into a concha of the user's ear. The extended
`ortion includes an aperture at an end thereof which aligns
`p
`p
`9.
`with the user's ear when the earphone is being worn by the
`user. The extended portion defines a passageway extending
`from the aperture to the internal cavity. The cushion covers
`at least part of the extended portion of the shell body and has
`an opening aligned with the aperture.
`
`45 Claims, 5 Drawing Sheets
`
`Petitioner's Exhibit 1141
`Page 001
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`

`

`U.S. Patent
`US. Patent
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`Jan. 27, 2004
`Jan. 27, 2004
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`Sheet 1 of 5
`Sheet 1 0f5
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`US 6,683,965 B1
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`Petitioner's Exhibit 1141
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`Page 002
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`Petitioner's Exhibit 1141
`Page 002
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`U.S. Patent
`US. Patent
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`Jan. 27, 2004
`Jan. 27, 2004
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`Sheet 2 0f5
`Sheet 2 of 5
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`US 6,683,965 B1
`US 6,683,965 B1
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`FIG. 3
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`Petitioner's Exhibit 1141
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`Page 003
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`Petitioner's Exhibit 1141
`Page 003
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`U.S. Patent
`US. Patent
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`Jan. 27, 2004
`Jan. 27, 2004
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`Sheet 3 of 5
`Sheet 3 0f5
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`US 6,683,965 B1
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`Petitioner's Exhibit 1141
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`Page 004
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`Petitioner's Exhibit 1141
`Page 004
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`U.S. Patent
`US. Patent
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`Jan. 27, 2004
`Jan. 27, 2004
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`Sheet 4 of 5
`Sheet 4 0f5
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`US 6,683,965 B1
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`Petitioner's Exhibit 1141
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`Page 005
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`Petitioner's Exhibit 1141
`Page 005
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`U.S. Patent
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`Jan. 27, 2004
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`Sheet 5 of 5
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`US 6,683,965 B1
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`|-|||||||ETT??TT??TT??
`Tl|||||||||)(|||||||||||||||)?',
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`F??????LL?TTL||||||||| || .
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`Petitioner's Exhibit 1141
`Page 006
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`

`

`1
`IN-THE-EAR NOSE REDUCTION
`HEADPHONES
`CROSS REFERENCE TO RELATED
`APPLICATIONS
`The following patent application is related to the present
`application: U.S. Ser. No. 08/261,802 filed Jun. 17, 1994,
`incorporated herein by reference. Also as background, ref
`erence is made to U.S. Pat. No. 5,305,387, issued Apr. 19,
`1994 also incorporated herein by reference.
`BACKGROUND OF THE INVENTION
`The invention generally relates to earphones, in particular,
`in-the-ear earphones, designed to provide noise attenuation.
`There are at least three headphone design types, which are
`generally categorized in terms of how they are worn by the
`user. The three design types are referred to as around-the-ear,
`on-the-ear, and in-the-ear headphones. Around-the-ear head
`phones have large earphones that resemble earmuffs. Like
`earmuffs, the around-the-ear earphone covers and Surrounds
`the ear. It typically provides very good noise attenuation but
`it is not particularly comfortable, especially for people using
`eyeglasses. Since the earphone Surrounds the user's ear, it
`cuts off air circulation behind the ear and thus can be
`uncomfortably warm in hot weather.
`In addition, under Some circumstances Such as when
`intelligibility of local conversation is important, the high
`level of passive attenuation provided at high frequencies by
`the around-the-ear headphones will cause intelligibility of
`external Stimuli to Suffer. There are many environments or
`applications in which it is desirable to hear external con
`Versation or Sound, for example, in certain industrial appli
`cations and in airplanes. In large industrial plants where a lot
`of machine noise is present, it may be useful to use radioS
`as a way of communicating with coworkers located else
`where in the plant. Because of the high noise levels, ear
`phones must be worn to hear the radio communications. To
`be effective, the earphones must also block out Some of the
`external noise. But if they block out too much of the external
`noise, the user will not be able to hear the conversations of
`nearby coworkers or the helpful Sound queues of operating
`machinery. In airplanes, the airline pilot needs headphones
`that effectively block out the external engine noises. But the
`pilot also needs to hear the conversation of people who are
`nearby, Such as their copilot or other airline Support Staff. In
`those applications, the around-the-ear headphones Some
`times can cause unacceptable degradation of intelligibility of
`the conversations of Such people.
`The on-the-ear headphone, which is also referred to as the
`Supra aural design, has an earphone cushion that Simply rests
`against the ear when the headphone is being worn by the
`user. Typically, the cushion is made of an open cell foam
`material that easily transmits Sound. This design tends to be
`lightweight, compact, and very comfortable. One
`disadvantage, however, is that conventional on-the-ear
`designs do not very effectively attenuate external noise.
`Thus, they are not well Suited for use in noisy environments.
`The in-the-ear headphone which typically provides leSS
`attenuation than the around-the-ear type has an earpiece that
`fits into the ear cavity, i.e., concha. Unlike the around-the
`ear design, however, the in-the-ear headphone is typically
`very light and compact and thus for that reason it can be very
`comfortable to wear.
`SUMMARY OF THE INVENTION
`In general, in one aspect, the invention is an in-the-ear
`headphone including an earphone which is placed onto a
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`user's ear. The earphone includes a shell body defining an
`internal cavity. The shell body has an extended portion
`shaped and sized to fit into a concha of the user's ear. The
`extended portion includes an aperture at an end thereof
`which aligns with the user's ear when the earphone is being
`worn by the user. The extended portion defines a passage
`way extending from the aperture to the internal cavity So that
`the internal cavity is acoustically coupled to the user's ear
`cavity when the headphone is being worn by the user. The
`earphone also includes a cushion covering at least part of the
`extended portion of the shell body and having an opening
`aligned with the aperture. The cushion may be made of a
`molded, Self-skinned material.
`Preferred embodiments include the following features.
`The cushion is made of a damped, compliant material and it
`includes bulbous portions near the opening and Surrounding
`at least Some of the aperture. The bulbous portions are in a
`range of about 3 to 5 millimeters in thickness. The internal
`cavity has a total Volume that is larger than 10 cubic
`centimeters (e.g. 20 cc.). The aperture is oval-shaped and has
`dimensions of about 3 to 3.5 mm by about 8 to 10 mm. (i.e.,
`it has an area that is between 25 to 35 mm'). The earphone
`further includes an acoustic damping material within the
`internal cavity (e.g. an open cell foam).
`In general, in another aspect, the invention is an in-the-ear
`headphone including an earphone which is placed onto a
`user's ear. The earphone includes a shell body defining an
`internal cavity. The shell body has an extended portion
`shaped and sized to fit into a concha of the user's ear. The
`extended portion includes an aperture at an end thereof
`which aligns with the user's ear when Said earphone is being
`worn by the user and it defines a passageway extending from
`the aperture to the internal cavity So that the internal cavity
`is acoustically coupled to the user's ear cavity when the
`headphone is being worn by the user. The earphone also
`includes an acoustical driver mounted within the extended
`portion; and an acoustical microphone mounted within the
`extended portion. The microphone is located Substantially
`between the driver and the aperture and near a lower edge of
`the aperture.
`In preferred embodiments, the aperture is oval Shaped and
`has a long axis and a short axis and the plane of the driver
`is Substantially parallel to the long axis of the oval-shaped
`aperture. The aperture is oriented So that its long axis is
`oriented vertically when the earphone is worn by the user.
`Also, the plane of the driver and the plane of the aperture are
`oriented at an angle of between 45 and 90 with respect to
`each other. The earphone also includes a hollow tower
`structure within the shell body. The tower structure holds the
`driver within the earphone and defines a rear cavity behind
`the driver. The rear cavity is Separate and Substantially
`isolated from the internal cavity. The rear cavity has a
`volume that is substantially smaller than the volume of the
`internal cavity (e.g. 2 cubic centimeters). A wall of the rear
`cavity is formed by a section of the shell body and it includes
`a Second aperture connecting the rear cavity to outside of the
`shell body. The Said Second aperture is covered by a material
`having an acoustic resistance. The tower Structure includes
`a pressure equalization hole connecting the rear cavity to the
`internal cavity. The preSSure equalization hole has a diam
`eter of less than about 1 millimeter (e.g. 0.25 and 0.5
`millimeters).
`Also in preferred embodiments, the plane of the micro
`phone is Substantially perpendicular to the plane of the
`driver and the plane of the microphone forms an angle with
`the plane of the aperture of between 45 and 60.
`The in-the-ear headphone of the invention protects a
`user's ears by actively and passively attenuating external
`
`Petitioner's Exhibit 1141
`Page 007
`
`

`

`3
`noise, which leaks into the users ear canal when the head
`phone is worn by the user, Such that the total attenuation of
`the System is relatively flat acroSS the audible frequencies.
`Total attenuation of better than about 15-25 dB is achievable
`with the invention. It has been shown that 20 db attenuation
`is Sufficient for good hearing protection and yet it still
`enables people to hear each other when communicating in an
`industrial environment.
`Other advantages and features will become apparent from
`the following description of the preferred embodiment and
`from the claims.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`FIG. 1 shows a headphone with left and right in-the-ear
`earphones,
`FIG. 2 is a side view of the in-the-ear earphone as it rests
`on a user's ear;
`FIG. 3 shows the cushion side of the earphone;
`FIG. 4A is a top view of a person wearing the headphones
`shown in FIG. 1;
`FIG. 4B is a cross-sectional view of the earphone cavity
`and cushion through section A-A in FIG.3 and which also
`shows a top view of how the earphone fits within a perSon's
`Car
`FIG. 5A is a front view of the headphones as they are
`being worn by a perSon;
`FIG. 5B is a cross-sectional view of the earphone through
`Section B-B of FIG. 3 and which also shows a front view
`of how the earphone fits within a person's ear;
`FIG. 6 shows a cross-sectional view of the earphone with
`driver and microphone through Section A-A of FIG. 3;
`FIG. 7 is a block diagram of an active attenuation circuit;
`FIG. 8 illustrates the total attenuation provided by the
`invention; and
`FIG. 9 shows an alternative design for the driver/
`microphone combination.
`DESCRIPTION OF THE PREFERRED
`EMBODIMENTS
`Referring to FIGS. 1, 2, 3, 4B and 5B, an in-the-ear
`headphone 10 has two earphones 12, one for the right ear
`and one for the left ear. Each earphone 12 includes a rigid
`shell 14 that defines an internal cavity 28 and that has an
`extended portion 16 which is sized and shaped to fit into the
`concha 18 of a user's ear 20. An oval-shaped aperture 22 at
`an end of the extended portion 16 aligns with the user's ear
`canal 24 to create an acoustical connection between the
`user's ear canal and internal cavity 28 when the headphone
`is worn by the user.
`Typically, an adult user's ear cavity, i.e., the combined
`Volume of the concha and the ear canal, is about two cubic
`centimeters (cc.) when the in-the-ear headphone is worn.
`Internal cavity 28 has a volume which is substantially larger
`than this. Theoretically, it can be shown that a volume that
`is about ten times the ear cavity Volume will produce a
`passive attenuation of about 20 db. Thus, in the described
`embodiment, internal cavity has a volume of greater than
`about 20 cc. The invention, however, is not limited to using
`internal cavity sizes which are that large; noticeable passive
`attenuation will occur with Smaller cavity sizes, e.g. 10 cc.
`A cushion 26 surrounds extended portion 16 of the shell
`and Surrounds aperture 22 without obstructing it. In other
`words, cushion 26 includes an opening that aligns with and
`is approximately the same Size as aperture 22. Cushion 26 is
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`typically made of a molded, Self Skinned material that has a
`Smooth Surface which is capable of creating a good acous
`tical Seal with user's ear. The material is also Soft and highly
`compliant, Such that it readily conforms to the human ear
`without having to apply much pressure. Additionally, the
`material is mechanically damped to give a low Sound
`transmission capability. Typically, a heavily damped mate
`rial also exhibits a slow recovery rate (e.g., on the order of
`Seconds) to its original shape after being compressed. A
`suitable material which exhibits all of these properties is a
`urethane foam, Such as is described in U.S. Pat. No. 4,158,
`087, or any other comparable material. Cushion 26 makes
`the headphones comfortable for the user to wear and, by
`forming a Seal at the region of contact with the user's ear,
`reduces the amount of external ambient Sound that is per
`mitted to leak into the user's ear canal.
`Referring to FIGS. 4B and 5B, in order to create an
`effective acoustical Seal with a wide range of different ear
`shapes and sizes, cushion 26 has bulbous or expanded
`portions 26a, 26c, and 26d adjacent to the back, top, and
`bottom areas, respectively, of aperture 22. Bulbous portions
`26a, 26c, and 26d of cushion 26 are thick enough to permit
`the cushion to compress and thereby conform to the different
`sizes and Shapes of ear that might be encountered. In the
`described embodiment, bulbous portions 26a, 26c, and 26d
`are approximately three to five millimeters thick. The other
`regions of cushion including front portion 26b are much
`thinner, e.g. approximately one mm thick.
`If extended portion 16 of shell 14 and cushion 26 are
`custom fitted to a particular user's ear, then cushion 26 can
`be made without bulbous portions 26a, 26c, and 26d. In
`other words, it can have Substantially uniform thickness (e.g.
`1 mm). Extended portion 16 can be custom molded to the
`shape of the concha of a user's ear by using a proceSS Similar
`to that used to custom mold hearing aids.
`As best seen in FIGS. 4B and 5B, extended portion 16 is
`curved along Substantially its entire length to Substantially
`match the curvature of Said concha and allow attachment
`around the extended portion of a cushion for establishing a
`Seal between the extended portion and the user's ear.
`Internal cavity 28 in combination with the user's ear
`cavity passively attenuates high frequency ambient noise. To
`improve the acoustic coupling between internal cavity 28
`and the ear cavity and thereby improve attenuation effi
`ciency of the earphone, aperture 22 is made as large as
`possible without compromising the cushion's ability to form
`a Seal with the user's ear. Indeed, the larger one makes the
`size of aperture, the greater will be the bandwidth over
`which substantially the full level of passive attenuation will
`be achieved. The size of aperture 22 is limited, however, by
`the Size of a typical user's ear. If aperture 22 is made too
`large, the cushion around aperture 22 will not make full
`contact with the user's ear at all locations Surrounding the
`aperture. Thus, there will be portions through which external
`noise will be able to leak into the ear canal and degrade the
`low frequency attenuation performance of the earphone. In
`the described embodiment, aperture 22 has an oval shape
`with the dimension along its short axis being about 3-3.5
`mm and the dimension along its long axis being by about
`8-10 mm. In other words, aperture 22 has a total area of
`about 25–35 mm. An opening of this size extends the full
`achievable level of passive attenuation of the earphone down
`to a cutoff frequency of about 700-800 Hz, while still
`allowing the cushion to achieve a good Seal with the wide
`variety of ear shapes and sizes that are likely to be encoun
`tered.
`To improve the acoustic characteristics of the earphone,
`internal cavity 28 is filled with a sound absorbent material 30
`
`Petitioner's Exhibit 1141
`Page 008
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`S
`(i.e., damping material), Such as an open cell foam or fibrous
`material Such as Thinsulate TM which is available from 3M
`(Minnesota, Mining and Manufacturing Corporation).
`Damping material 30 produces a more predictable, Smoother
`transfer function and reduces cavity resonances.
`Referring to FIG. 6, a driver 32 and a microphone 34 are
`mounted within internal cavity 28. As will be described
`below, they are used to actively attenuate higher frequency
`noise. Both driver 32 and microphone 34 are disk-shaped
`devices. Driver 32 is mounted inside of extended portion 16
`of shell 14 and is oriented such that the plane of the
`disk-shaped driver is Substantially parallel to the long axis of
`oval-shaped aperture 22 and forms an angle with the plane
`in which aperture 22 lies of between 45 to 90, preferably
`closer to 90 (i.e., perpendicular). This particular orientation
`of driver 32 allows extended portion 16 of shell 14 to be
`made narrow enough So as to fit into a wide variety ear Sizes.
`The orientation of driver 32 also is such as to present only
`minimal obstruction of a passageway 29 that extends
`through extended portion 16 and connects aperture 22 to the
`rest of internal cavity 28.
`Microphone 34 is mounted on the edge of driver 32 and
`inside the extended portion 16, near aperture 22. More
`Specifically, it is located near the lower Side of aperture 22
`and Substantially between driver 32 and aperture 22. Micro
`phone 34 is attached to the edge of driver 32 so that the plane
`in which it lies is Substantially perpendicular to the plane in
`which driver 32 lies and angled slightly toward the plane of
`aperture 22 (e.g. forming an angle of between 45 and 60).
`The front of microphone 34 faces upwards from the bottom
`of aperture 22 as indicated in FIGS. 3 and 6. In other words,
`microphone 34 is as close as possible to aperture 22, without
`obstructing aperture 22 and without extending out of aper
`ture 22. Its location and orientation relative to driver 32 and
`aperture 22 produces minimum delay coupling between
`microphone 34 and driver 32 and particularly effective
`active noise cancellation in the region in which it is most
`desired, i.e., the user's ear cavity.
`Driver 32 is a high compliance, high excursion driver
`which is between 15 to 20 mm in diameter. In the described
`embodiment, it is a Model TO16HO2 which is available
`from Foster of Japan. Microphone 34 is a much smaller
`diameter (e.g., six millimeter) device such as an EM 109
`electric microphone available from Primo, Inc. of Japan (or
`an equivalent device).
`Referring again to FIG. 6, both driver 32 and microphone
`34 are mounted at one end of a hollow tower structure 42
`within internal cavity 28. The opposite end of tower struc
`ture 42 is attached to a back wall of shell 14. Driver 32 is
`held within tower structure 42 by a flexible rubber or
`silicone grommet 36 which forms a seal between driver 32
`and tower structure 42 around the perimeter of driver 32.
`Tower structure 42 defines a separate rear cavity 44 behind
`driver 32 that is smaller than and substantially isolated from
`internal cavity 28. In the described embodiment, rear cavity
`44 has a volume of approximately two cubic centimeters
`and, like internal cavity 28, it is also filled with a damping
`material 50.
`Grommet 36 is constructed so as to hold microphone 34
`in position relative to driver 32. Due to the flexibility of the
`material of which grommet 36 is made, grommet 36 facili
`tates easy assembly of the earphone. Both driver 32 and
`microphone 34 can be easily slipped into their correspond
`ing holes within grommet 36 and then grommet 36 can be
`easily inserted into the end of tower structure 42.
`Shell 14 includes a circular opening 46 defining a pas
`Sageway between rear cavity 44 and the outside. Opening 46
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`is covered with a resistive mesh 48. In the described
`embodiment, opening 46 has a diameter of approximately
`five mm and mesh 48 creates a resistance for opening 46 of
`approximately 1–2x10 acoustic ohms. The combination of
`the resistive mesh 48 and damping material 50 provides a
`controlled damping of driver 32 and it passively attenuates
`higher frequency noise which passes through driver 32 from
`the outside.
`Shell 14 includes a pressure equalization hole 49, of about
`0.25 to 0.5 millimeters in diameter, which enables pressure
`within the internal cavity 38 to equalize when the earphone
`is placed on the user's ear. In the described embodiment,
`equalization hole 49 passes through the backside of shell 14
`So as to connect internal cavity 28 to the outside.
`Alternatively, pressure equalization hole 49 can be located in
`the wall of tower structure 42 thereby connecting internal
`cavity 28 with rear cavity 44. The acoustic resistance of this
`hole is about 1-2x10" acoustic ohms.
`When a user is wearing the headphones, cushion 26
`contacts the user's ear and forms a Seal that tends to prevent
`air from entering or escaping from the enclosed region
`which is made up of the user's ear canal and internal cavity
`28. Without a pressure equalization hole, movement of the
`headphones on the user's will tend to cause Severe over
`preSSure or under pressure conditions to occur within this
`enclosed region. This will typically make the earphones
`uncomfortable, may cause them to float or creep on the ear,
`and will tend degrade the acoustic Seal between the cushion
`and the user's ear (and thereby degrade the passive
`attenuation). Pressure equalization hole 49, by allowing air
`to enter and leave internal cavity 28, prevents the over
`preSSure and under pressure conditions from occurring.
`An active attenuation circuit 60 of which driver 32 and
`microphone 34 form a part is shown in FIG. 7. Circuit 60 is
`duplicated for the other driver/microphone combination of
`the other earphone. Earphone 12 is represented by the
`dashed box and the driver and the microphone are identified,
`as before, by numbers 32 and 34, respectively. Driver 32
`reproduces Sound for a listener wearing the headphones and
`microphone 34 picks up this Sound and low frequency
`ambient Sound that is present in a cavity that exists between
`the earphone and the listener's ear. A preamplifier 66 ampli
`fies the output Signal from microphone 34 to produce a
`feedback Signal that is fed back to a combiner circuit 62 at
`the input side of the circuit. Combiner circuit 62 adds the
`feedback signal to an input Signal V, which represents the
`audio that is to be reproduced by the driver 32. The output
`of combiner circuit 62 passes first through a compressor
`circuit 68 which limits the amplitude of high level signals
`and then through a compensator circuit 70 which insures that
`the open-loop gain of the System meets the Nyquist Stability
`criteria and thus does not oscillate.
`The output of compensator circuit 70 passes to a power
`amplifier 72 and then to driver 32. Power amplifier 72
`amplifies the Signal to the level required for producing the
`desired Sound level out of driver 32. The audio Sound
`generated by driver 32 combines with ambient noise
`(identified as P in FIG. 7) that leaks by the earphone
`cushion into the cavity formed between the earphone and the
`listener's ear. Thus, the Signal that microphone 34 picks up
`represents the audio Signal plus the ambient noise.
`The active attenuation circuit attenuates noise over the
`low frequency range, e.g. below 700-800 Hz. It is possible
`to increase the point at which the active attenuation rolls off,
`but this would be at the risk of making the system unstable.
`Noise at the higher frequencies is passively attenuated by the
`
`Petitioner's Exhibit 1141
`Page 009
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`7
`internal cavity coupled with the user's ear cavity. AS noted
`previously, the low frequency cutoff of the passive attenu
`ation is controlled in part by the Size of aperture 22. If
`aperture 22 is made larger the effectiveness of the passive
`attenuation will extend to lower frequencies. With the aper
`ture size used in the described embodiment (e.g. 25-35
`mm), the passive attenuation extends down to about
`700-800 HZ.
`Referring to FIG. 8, the total attenuation, line 80, pro
`vided by the headphones of the invention is a combination
`of active attenuation represented by curve 82 and passive
`attenuation represented by curve 84. The combination of
`active and passive attenuation provides a Substantially flat
`attenuation of about 15-25 db across the audible frequen
`CCS.
`Referring to FIG. 9, in an alternative embodiment, micro
`phone 34 is modified by drilling a hole 90 in its back side.
`(Note that this drawing shows the microphone mounted in
`Such a way that its back Side is visible in the drawing;
`whereas FIG. 6 shows the microphone mounted so that its
`front side is visible.) The hole 90 is acoustically coupled to
`the outside of the shell (or alternatively to rear cavity 44)
`through conduit 92 and an equalization hole 94 in the wall
`of shell 14.
`The advantage of this configuration, from a System sta
`bility point of View, is that the low frequency response of the
`microphone 34 becomes less of a factor, and from a control
`point of view, the clipping level of the System is increased
`at low frequencies. From an ambient noise point of view, the
`frequency response of the microphone will have first order
`roll-off (like a velocity microphone). By proper selection of
`the size of the equalization hole 90, it is possible to increase
`the maximum level of the ambient noise that the System can
`accept before clipping. Typically the pressure equalization
`hole should be chosen to provide roll-off at about thirty hertz
`without Significantly affecting cancellation above one hun
`dred hertz.
`Other embodiments are within the following claims.
`What is claimed is:
`1. An in-the-ear earphone which is placed on a user's ear,
`Said earphone comprising,
`a shell body defining an internal cavity, Said shell body
`having an extended portion shaped and sized to fit into
`a concha of the user's ear, Said extended portion
`including an aperture at an end thereof which aligns
`with the user's ear when Said earphone is being worn by
`the user, Said extended portion defining a passageway
`extending from Said aperture to Said internal cavity So
`that Said internal cavity is acoustically coupled to the
`user Bear cavity when the headphone is being worn by
`the user,
`Said extended portion being curved along Substantially its
`entire length to Substantially match the curvature of
`Said concha and allow attachment around Said extended
`portion of a cushion for establishing a Seal between Said
`extended portion and the user's ear.
`2. The in-the-ear earphone according to claim 1 further
`comprising a cushion covering at least part of Said extended
`portion of Said shell body and having an opening aligned
`with Said aperture.
`3. The in-the-ear earphone according to claim 2, wherein
`Said cushion is made of a molded, Self-skinned material.
`4. The in-the-ear earphone according to claim 2 wherein
`Said cushion is made of a mechanically-damped compliant
`material.
`5. The in-the-ear earphone according to claim 2 wherein
`Said cushion includes a bulbous portion near the opening and
`Surrounding at least Some portions of Said aperture.
`
`15
`
`25
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`US 6,683,965 B1
`
`8
`6. The in-the-ear earphone according to claim 5 wherein
`said bulbous portion is in a range of about 3 to 5 millimeters
`in thickness.
`7. The in-the-ear earphone according to claim 1, wherein
`Said internal cavity is significantly larger than the ear canal
`of an average user.
`8. The in-the-ear earphone according to claim 7 wherein
`Said internal cavity has a total Volume that is larger than 10
`cubic centimeters.
`9. The in-the-ear earphone according to claim 8 wherein
`said internal cavity has a total volume that is about 20 cubic
`centimeters.
`10. The in-the-ear earphone according to claim 7 wherein
`Said aperture is oval-shaped.
`11. The in-the-ear earphone according to claim 10
`wherein said aperture has dimensions of about 3 to 3.5 mm
`by about 8 to 10 mm.
`12. The in-the-ear earphone according to claim 10
`wherein Said aperture has an area that is greater than about
`25 Square millimeters.
`13. The in-the-ear earphone according to claim 12
`wherein Said aperture has an area that is in the range of about
`25 to 35 square millimeters.
`14. The in-the-ear earphone according to claim 7 wherein
`Said extended portion is custom moldable to the concha of
`the user.
`15. The in-the-ear earphone according to claim 7 wherein
`Said earphone further comprises an acoustic damping mate
`rial within Said internal cavity.
`16. The in-the-ear earphone according to claim 15
`wherein Said damping material is made of an open cell foam.
`17. An in-the-ear earphone which is placed on a user's ear,
`Said earphone comprising:
`a shell body defining an internal cavity, Said shell body
`having an extended portion shaped and sized to fit into
`a concha of the user's ear, Said extended portion
`including an aperture at an end thereof which aligns
`with the user's ear when Said earphone is being worn by
`the user, Said extended portion defining a passageway
`extending from Said aperture to Said internal cavity So
`that Said internal cavity is acoustically coupled to the
`user's ear cavity when the earphone is being worn by
`the user;
`an acoustical driver mounted within Said extended por
`tion; and
`an acoustical microphone mounted within Said extended
`portion, Said microphone located Substantially between
`Said driver and Said aperture and near a lower edge of
`Said aperture;
`Said extended portion being curved along Substantially its
`entire length to Substantially match the curvature of
`Said concha and allow attachment around Said extended
`portion of a cushion for establishing a Seal between Said
`extended portion and the user's ear.
`18. The in-the-ear earphone of claim 17 wherein said
`aperture is oval shaped and has a long axis and a short axis,
`wherein Said driver lies in a first plane, and wherein Said first
`plane is Substantially parallel to the long axis of Said
`oval-shaped aperture.
`19. The in-the-ear earphone of claim 17 wherein said
`aperture lies Substantially within a Second plane and where
`Said first plane and Said Second plane are oriented at an angle
`of between 45 and 90 with respect to each other.
`20. The in-the-ea