PATENT DOCUMENT

Publication Number: US-8767994-B2
Application Number: US-95085210-A
Country: US
Kind Code: B2

Title: Gas filled speaker volume

Abstract:
A speaker enclosure includes a gas cavity and an air cavity separated by a flexible membrane. A diaphragm is located roughly in an opening of the enclosure surrounding the gas cavity and attached to the enclosure by an outer suspension member. The enclosure, the flexible membrane, the diaphragm, and the outer suspension member are gas and air impermeable. The enclosure surrounding the air cavity has a vent hole to allow air to travel into and out of the air cavity for barometric pressure equalization of the gas cavity. Other embodiments are also described and claimed.

Claims:
What is claimed is: 
     
       1. A speaker system, comprising:
 a gas-impermeable diaphragm; and 
 a rigid enclosure made of gas-impermeable material and having an interior partition to separate a gas cavity and an air cavity, the interior partition having a first opening to the gas cavity sealed by a gas-impermeable flexible membrane comprising a sheet of material that extends across the first opening, the enclosure having a second opening to the gas cavity, the diaphragm being coupled to the enclosure through a gas-impermeable suspension member wherein the second opening is sealed by the suspension member and the diaphragm, the enclosure having a vent hole to allow air to travel into and out of the air cavity for barometric pressure equalization. 
 
     
     
       2. The speaker system of  claim 1  wherein the gas cavity contains a gas that is less dense than air, and no air. 
     
     
       3. The speaker system of  claim 2  wherein the gas is selected from a group consisting of helium and hydrogen. 
     
     
       4. The speaker system of  claim 2  further comprising a gas emitter within the gas cavity to replenish leaked gas. 
     
     
       5. The speaker system of  claim 4  wherein the gas emitter includes a mineral containing uranium or thorium that decays to emit helium. 
     
     
       6. The speaker system of  claim 1  further comprising a drive assembly having a coil and a magnet, the drive assembly is attached to the diaphragm and to the enclosure to vibrate the diaphragm in response to an input electrical audio signal. 
     
     
       7. The speaker system of  claim 6  further comprising a speaker frame to which the suspension member and the drive assembly are attached, wherein the speaker frame seals off the second opening and is inside the gas cavity. 
     
     
       8. The speaker system of  claim 6  wherein the drive assembly is located inside the enclosure, the enclosure having a gas-impermeable electrical signal port to allow transfer of an electrical audio signal into the enclosure. 
     
     
       9. An apparatus, comprising:
 a mobile electronics device housing having integrated therein a speaker module having a rigid enclosure made of gas-impermeable material, the rigid enclosure having an interior partition to separate a gas cavity and an air cavity, the interior partition having a first opening sealed by a gas-impermeable flexible membrane comprising a sheet of material that extends across the first opening, the enclosure surrounding the gas cavity having a second opening that is sealed by a gas-impermeable diaphragm and a gas-impermeable suspension member and that allows acoustic waves to emanate from the diaphragm when the diaphragm vibrates in response to an input electrical audio signal, the enclosure surrounding the air cavity having a vent hole to allow air to travel into and out of the air cavity for barometric pressure equalization. 
 
     
     
       10. The mobile device of  claim 9  wherein the gas cavity contains a gas that is less dense than air, and no air. 
     
     
       11. The mobile device of  claim 10  wherein the gas is selected from a group consisting of helium and hydrogen. 
     
     
       12. The mobile device of  claim 9  wherein the speaker module includes a gas emitter within the gas cavity to replenish leaked gas. 
     
     
       13. The mobile device of  claim 12  wherein the gas emitter includes a mineral containing uranium or thorium that decays to emit helium. 
     
     
       14. The mobile device of  claim 9  wherein the speaker module includes a drive assembly having a coil and a magnet, the drive assembly is attached to the diaphragm and to the enclosure to vibrate the diaphragm in response to the input electrical audio signal. 
     
     
       15. The mobile device of  claim 14  wherein the drive assembly is rigidly attached to the enclosure by a speaker frame and is located completely inside the gas cavity. 
     
     
       16. The mobile device of  claim 9  wherein the enclosure surrounding the gas cavity has a gas-impermeable electrical signal port to allow transfer of an electrical audio signal into the speaker module. 
     
     
       17. A speaker system, comprising:
 a gas cavity sealed by a rigid gas-impermeable enclosure, a gas-impermeable flexible membrane, and a gas-impermeable suspension member to which a gas-impermeable diaphragm is attached; and 
 an air cavity separated from the gas cavity by the gas-impermeable flexible membrane, the air cavity having a vent hole to allow air to travel into and out of the air cavity for barometric pressure equalization of the gas cavity; 
 wherein the gas-impermeable flexible membrane comprises a sheet of material that extends across an opening between the as cavity and the air cavity. 
 
     
     
       18. The speaker system of  claim 17  wherein the gas cavity contains a gas that is less dense than air, and no air. 
     
     
       19. The speaker system of  claim 18  wherein the gas is selected from a group consisting of helium and hydrogen. 
     
     
       20. The speaker system of  claim 17  wherein the gas cavity is sealed by a gas-impermeable speaker frame to which the suspension member is attached. 
     
     
       21. The speaker system of  claim 20  wherein the gas cavity houses a drive assembly having a coil and a magnet, the drive assembly is attached to the speaker frame and the diaphragm. 
     
     
       22. The speaker system of  claim 17  wherein the gas cavity is sealed by a gas-impermeable electrical signal port.

Description:
The various embodiments of the invention relate to speaker systems and more specifically, to a gas filled volume of a speaker enclosure used in, for instance, a mobile device such as a smartphone. 
     BACKGROUND 
     In most speaker systems, a vibrating diaphragm is mounted at an opening of a speaker enclosure. A common type of speaker enclosure is a sealed enclosure. In a sealed speaker enclosure, the diaphragm compresses air in the enclosure when it moves in and rarefies air when it moves out. In smaller speaker and enclosure designs, substantial back pressures are exerted against the vibrating diaphragm by the air within the enclosure. This back pressure retards the movement of the diaphragm and degrades the quality of the sound being reproduced. To effectively enlarge the volume of the speaker enclosure, the air within the enclosure can be replaced with a gas that is less dense than air. 
     However, with mobile devices, the barometric air pressure surrounding the speaker enclosure can decrease or increase abruptly, for example when the user is riding in an elevator. This will result in a net force being exerted on the diaphragm of the sealed speaker system, causing it to “stick” and therefore stop producing sound until the pressure inside the speaker has equalized with the barometer pressure (due to leakage). In air speaker systems, such barometric equalization is achieved relatively quickly (in order to prevent noticeable sticking of the diaphragm), by adding a small vent hole to the enclosure (at the expense of a small amount of sound quality degradation). This solution however will not work for an enclosure that is filled with gas and no air. 
     SUMMARY 
     A speaker system for enlarging the effective volume of a speaker enclosure is described. The speaker system includes a speaker enclosure having an interior partition to separate a gas cavity and an air cavity. A diaphragm is located at an opening of the enclosure surrounding the gas cavity. The gas cavity is filled with a gas that is less dense than air (e.g., helium or hydrogen) to effectively enlarge the volume of the gas cavity. The interior partition separating the gas cavity and the air cavity has an opening that is sealed by a flexible membrane. The enclosure surrounding the air cavity has a vent hole to allow the surrounding air to travel into and out of the air cavity. 
     As the air pressure surrounding the speaker enclosure decreases, the gas inside the enclosure will be allowed to expand. The flexible membrane between the gas cavity and the air cavity may allow the gas to expand without significantly increasing the net force on the diaphragm as the vent hole will allow air to travel out of the air cavity. Similarly, when the air pressure surrounding the speaker enclosure increases, the gas within the enclosure will be allowed to contract. The vent hole will allow the air to travel into the air cavity, and the flexible membrane will allow the gas to contract without creating a vacuum on the diaphragm. Therefore, there is very little pressure change on the diaphragm when the barometric pressure changes. 
     The above summary does not include an exhaustive list of all aspects of the present invention. It is contemplated that the invention includes all systems and methods that can be practiced from all suitable combinations of the various aspects summarized above, as well as those disclosed in the Detailed Description below and particularly pointed out in the claims filed with the application. Such combinations have particular advantages not specifically recited in the above summary. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of the invention will now be described with reference to the drawings summarized below. The embodiments of the invention are illustrated by way of example and not by way of limitation in the figures of the accompanying drawings in which like references indicate similar elements. It should be noted that references to “an” or “one” embodiment of the invention in this disclosure are not necessarily to the same embodiment, and they mean at least one. 
         FIG. 1  is a sectional view of a speaker system according to an embodiment. 
         FIG. 2  is a perspective view of the speaker system of  FIG. 1 . 
         FIG. 3  is a sectional view of a speaker showing details of the drive assembly. 
         FIG. 4  is a perspective view of an example media device. 
         FIG. 5  is a functional block diagram of the example media device. 
         FIG. 6  is a sectional view of a speaker system according to another embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Several embodiments of the invention with reference to the appended drawings are now explained. Whenever the shapes, relative positions, and other aspects of the parts described in the embodiments are not clearly defined, the scope of the invention is not limited only to the parts shown, which are meant merely for the purpose of illustration. Also, while numerous details are set forth, it is understood that some embodiments of the invention may be practiced without these details. In other instances, well-known circuits, structures, and techniques have not been shown in detail so as not to obscure the understanding of this description. 
     Referring to  FIG. 1 , the speaker system according to an embodiment of the invention may include an enclosure  100  made of rigid material that is air and gas impermeable, for example, aluminum or plastic. The “gas” here refers to less dense than air gases, such as hydrogen and helium. The enclosure  100  has an interior partition  110  that may also be made of the same rigid material, for example, as a single extrusion or molded piece. The interior partition  110  has an opening that is sealed by a flexible membrane  112  as shown. The interior partition  110  and the flexible membrane  112  separate a gas cavity  120  from an air cavity  130 . The interior partition  110  and the flexible membrane  112  are air and gas impermeable to seal off the gas cavity  120  from the air cavity  130 . 
     The enclosure  100  surrounding the gas cavity  120  has an opening in which a vibratable diaphragm, or cone,  140  is located. The diaphragm  140  is attached to the enclosure  100  by an outer suspension member, also referred to as an edge or a surround,  142  as shown in  FIG. 2  and  FIG. 3 . The surround  142  is flexible to allow the diaphragm  140  to vibrate in order to produce sound or acoustic pressure waves. As seen in  FIG. 1 , the enclosure surrounding the gas cavity  120  may have at least one, here two, electrical signal ports  102  and  104  to allow transfer of electrical audio signals into the enclosure. The enclosure  100 , the diaphragm  140 , the surround  142 , and the electrical signal ports  102  and  104  are air and gas impermeable to seal off the gas cavity  120  completely from the air (atmosphere) surrounding the outside of the enclosure  100 . 
     In addition to the diaphragm  140  and the surround  142 , the speaker may have a drive assembly  150 . As shown in  FIG. 3 , the drive assembly  150  may have a coil  154  and a magnet  156 . The coil  154  may be attached to the diaphragm  140 , and the magnet  156  may be rigidly attached to the enclosure  100  by a rigid frame, or basket,  148 . In this embodiment, the drive assembly  150  is located completely within the gas cavity  120  (see  FIG. 1 ). When an input electrical audio signal is applied to the coil  154  through the electrical signal wires  106  and  108 , a magnetic field is created by the current in the coil  154 . The coil  154  and the magnet  156  interact, generating a mechanical force that causes the coil  154  and the diaphragm  140  to vibrate in accordance with the input audio signal, producing sound per the input audio signal. 
     The speaker may also include a suspension system to keep the coil  154  centered in the gap of the magnet  156  and to provide a restoring force that returns the diaphragm  140  to a neutral position after vibrating. In addition to the surround  142 , the suspension system may include an inner suspension member, or a spider,  144  as shown in  FIG. 3 . The spider  144  connects the diaphragm  140  or coil  154  to the frame  148 . The spider  144  provides the majority of the restoring force to the diaphragm  140 , and the surround  142  keeps the diaphragm  140  and the coil  154  centered. 
     Referring again to  FIG. 1 , the gas cavity  120  is filled with a gas and no air. The gas is less dense than air to effectively enlarge the volume of the gas cavity  120  so that the diaphragm  140  sees a larger compliance than it would with air. Examples of a gas that is less dense than air may include helium and hydrogen. Despite being completely sealed off, the gas may leak out of the gas cavity  120  over time. A gas emitter  124  may be placed in the gas cavity  120  or in gas communication therewith, within the enclosure  100 , to replenish the leaked gas. The gas emitter  124  may be a mineral that decays to emit the gas. For example, minerals containing uranium or thorium decay to emit helium. For hydrogen, a hydrogen-rich chemical compound such as water used with a small electrolysis station may be used to emit hydrogen, for example, as part of a hydrogen fuel cell. 
     The gas inside the gas cavity  120  can expand and contract in response to pressure changes in the surrounding air as typically experienced by a consumer electronic personal mobile device; e.g., a smartphone, a digital music player, and a laptop computer. The flexible membrane  112  is flexible enough to allow this to occur, so as to not create a pressure delta across the diaphragm  140 . The enclosure  100  surrounding the air cavity  130  protects the flexible membrane  112  from becoming damaged. The enclosure  100  surrounding the air cavity  130  has a vent hole  132  that allows air to travel into and out of the air cavity  130  for barometric pressure equalization of the gas cavity  120 , by allowing the outer surface of the membrane  112  to remain at and follow the atmospheric pressure changes, such as when the speaker is in a moving elevator. 
     The membrane  112  is flexible relative to the enclosure  100  which is deemed rigid, as well as to the diaphragm  140 . The membrane  112  may be a piece of latex or other similarly long-lived, gas impermeable sheet or layer that can be bonded to the edge of the enclosure  100  at the opening. The sheet or layer needs to be sufficiently compliant so as to allow the gas in the gas cavity  120  to expand and contract quickly while riding in an elevator, for example, so as to avoid sticking of the diaphragm  140 . The membrane  112  and its associated enclosure opening may be larger than shown in  FIG. 1 , for example, almost as large as an entire sidewall of the enclosure  100 .  FIG. 2  shows an embodiment where the enclosure is essentially a hexahedron. Alternatively, the enclosure  100  could have any suitable three-dimensional solid shape, such as a polyhedron. 
     Referring to  FIG. 4 , the speaker system of  FIG. 1  may be integrated within the housing of a personal mobile electronics device  400 . The speaker may be, for example, an earpiece speaker or a speakerphone speaker that is used during a wireless telephone call, or for playing back digital music and/or audio-video files that have been downloaded into the device  400 . The housing  402  includes a speakerphone speaker housing acoustic aperture  422  that may be located in proximity to a lower portion of the mobile device  400  (referred to here as the bottom end). The bottom end may also contain a microphone, with associated microphone acoustic aperture  414  in the housing  402 . In certain embodiments, the microphone aperture  414  and/or the speaker aperture  422  may be located on a bottom  424  of the mobile device  400 . More generally, the microphone aperture  414  and the speaker aperture  422  may be located on any other portion of the housing  402  that can facilitate the delivery and reception of sound in the manner in which the device  400  is intended to be used. 
     In one embodiment, the housing  402  includes a first housing portion  404  and a second housing portion  406  that are fastened together to encase various electronic components of the mobile device  400 . The housing  402  may be made of polymer-based materials that are formed by, for instance, injection molding to define the form factor of the mobile device  400 . The housing  402  may surround and/or support internal components, such as circuit boards having integrated circuit components, internal radio frequency circuitry, an internal antenna, a speakerphone speaker, a microphone, an earpiece speaker, nonvolatile mass storage such as nonvolatile solid state memory and/or a magnetic rotating disk drive, as well as other components. The housing  402  also provides for the mounting of a built-in display  408 , a keypad  410 , an earphone jack  416 , and a battery charging jack (not shown). As an alternative to the separate display  408  and keypad  410 , a single touch sensitive display that spans most of the area on the front face of the device  400  may be provided, for both showing information to the user, as well as accepting input by the user. In this particular embodiment, the mobile device  400  can be used as a wireless telephony handset, where the earpiece speaker aperture  412  is positioned at the top end of the palm-sized mobile device  400  to facilitate such use of the device  400 . 
     The mobile device may include a wireless communications function, such as cellular or satellite telephony, pager, portable laptop/notebook computer, or other wireless communications function. The mobile device  400  may be, for example, an iPod or iPhone mobile device, or a palm sized personal computer such as an iPAQ Pocket PC available from Hewlett Packard, Inc., of Palo Alto, Calif. In some embodiments, the mobile device may synchronize with a remote computing system or server, to receive media using either a wireless or wireline communication path. Media may include sound or audio files, music, video, and other digital data, in either streaming and/or discrete (e.g., files) formats. The mobile device  400  may also have a wireline communication connector (not shown in  FIG. 4 ), e.g. a 30-pin docking connector, that may be located on the bottom face of the device  400 . This can be used to directly connect (e.g., dock) the device  400  to another computer. 
     Turning now to  FIG. 5 , a simplified functional block diagram of the mobile device  400 , according to an embodiment of the invention, is shown. An applications processor  502  may control the operation of many functions and other circuitry in the mobile device  400 . The processor may, for example, drive the display  408  and may receive user inputs through the user interface  506  (which may be integrated with the display  408  as part of a single, touch sensitive display panel on the front face of the device  400 ). Storage  504  may be comprised of nonvolatile solid state memory and/or a kinetic nonvolatile storage device (e.g., rotating magnetic disk drive) that stores the different digital media  544  (e.g., music and video files, functional software, preference information, e.g., for media playback, transaction information, e.g., information such as credit card information and other user authentication information, and wireless connection information, e.g., information that may enable the mobile device to establish wireless communication with another device). 
     In addition to the storage  504 , there may be memory  520 , also referred to as main memory or program memory, to store code and data being executed by the processor. Memory  520  may be comprised of solid state random access memory. A bus  518  provides a data transfer path between the memory  520 , storage  504 , and the processor  502 . In addition, the bus  518  may also allow communications with an audio coder/decoder (codec)  512  that is a specialized circuit that converts a digital audio signal into an analog signal for driving the speakerphone speaker  524  and/or the earpiece speaker  528 . This is designed to produce sound, including voice, music and other like audio. The codec  512  may also convert sound detected by the microphone  526  into digital audio signals for storage and digital processing by the processor  502 . 
     The mobile device  400  may also include a radio receiver  530 , which is coupled to an antenna  534 . The radio receiver  530  may be connected to an audio signal processor  532  that converts a received downlink signal (e.g., a cellular telephone signal or a wireless local area network signal from a base station) through demodulation and decoding into a digital audio signal. The digital audio signal may then be transferred to the audio codec  512  on bus  518  for conversion into an analog signal for driving the speakerphone speaker  524 . 
     All of the functionality shown in  FIG. 5  may be integrated within a single housing that makes the mobile device  400  a portable computing device that is battery or fuel cell operated and is palm sized. In other embodiments, however, the mobile device  400  may be somewhat larger than palm size, e.g. a laptop or notebook computer, yet nevertheless, is still considered a personal, consumer grade, stand alone mobile computing or media processing device. 
     While  FIG. 5  depicts a functional block diagram of the device  400  in terms of mostly hardware components, there are also several software components that control and manage, at a higher level, the different functions of the media device  400 . For instance, there may be a telephone application  540  that configures a built-in touch sensitive display to look like the keypad of a traditional telephony handset, and allows the user to enter a telephone number to be called, or select a previously stored number from a telephone address book. The application  540  may register the media device as a cellular handset with the nearest cellular base station (using the appropriate cellular communications protocols built into the media device). The application  540  then proceeds to allow the user to make a call, and controls the built-in microphone  526  and earpiece speaker  528  to enable the user to experience a two-way conversation during the call. Another application may be a media player application  542 , such as an MP3 audio player. This would allow the user to select songs as MP3 files that have been downloaded into the media device, for playback through the built-in speakerphone speaker  524  or through the earphone jack  416  (see  FIG. 4 ). 
       FIG. 6  shows the speaker system according to another embodiment, namely an earphone that may be plugged in to the earphone jack  416  of  FIG. 4 . The earphone may have an enclosure  600  made of rigid material that is air and gas impermeable, e.g., plastic. The enclosure  600  has an interior partition  610  that may also be made of rigid material. The interior partition  610  has an opening that is sealed by a flexible membrane  612 . The interior partition  610  and the flexible membrane  612  separate a gas cavity  620  from an air cavity  630 . The interior partition  610  and the flexible membrane  612  are air and gas impermeable to seal off the gas cavity  620  from the air cavity  630 . The air cavity  630  is open to the atmosphere through a vent hole  632  formed in an exterior wall of the enclosure  600 . 
     The enclosure  600  surrounding the gas cavity  620  has an opening through which acoustic waves produced by the diaphragm  640  can emanate. The diaphragm  640  is attached to the enclosure  600  by a surround, similar to the surround  142  of  FIG. 2  and  FIG. 3 , and protected by a screen, or a grill,  660  in the opening. The surround is flexible to allow the diaphragm  640  to vibrate in order to produce sound or acoustic pressure waves. The speaker of  FIG. 6  may include a drive assembly  650  and a suspension system similar to that shown in  FIG. 3 , although at a smaller size. The enclosure surrounding the gas cavity  620  may have two electrical signal ports  602  and  604  to allow transfer of an electrical audio signal and a return signal, into the enclosure. The enclosure  600 , the diaphragm  640 , the surround, and the electrical signal ports  602  and  604  are air and gas impermeable to seal off the gas cavity  620  completely from the air (atmosphere) surrounding the outside of the enclosure  100 . 
     The gas cavity  620  is filled with a gas and no air. The gas is less dense than air to effectively enlarge the volume of the gas cavity  620  so that the diaphragm  640  sees a larger compliance than it would with air. Despite being completely sealed off, the gas may leak out of the gas cavity  620  over time. A gas emitter  624  may be placed in the gas cavity  620  or in gas communication therewith, within the enclosure  600 , to replenish the leaked gas. 
     The gas inside the gas cavity  620  can expand and contract in response to or in accordance with surrounding air pressure changes caused by, for instance, riding in an elevator. The flexible membrane  612  enables this to occur so as to not create a pressure delta across the diaphragm  640 . The enclosure  600  surrounding the air cavity  630  has a vent hole  632  that allows air to travel into and out of the air cavity  630  for barometric pressure equalization of the gas cavity, by allowing the outer surface of the membrane  612  to remain at and follow the atmospheric pressure changes, such as when the speaker is in a moving elevator. The enclosure  600  surrounding the air cavity  630  may also protect the flexible membrane  612  from becoming damaged. 
     The various embodiments of the speaker system, as shown in  FIG. 1  and  FIG. 6 , may be manufactured in any manner that makes it suitable for operation as described above. For instance, a polyhedron or other suitable shell with an interior partition and two openings may be formed by, for example, using an injection molded plastic manufacturing process, to create the enclosure. Alternatively, the enclosure may be formed by joining (e.g., bonding) two separate halves or pieces of the shell together. A pair of electrical signal contacts may then be installed on the enclosure such that an electrical signal can pass through the enclosure while preventing the gas from leaking out of the enclosure. A gas emitter may be installed into the enclosure, or a gas port may be installed in the enclosure (to be connected to a hydrogen emitter or fuel cell outside the enclosure). A speaker frame of a speaker assembly (including the drive assembly, diaphragm, and surround already installed) may be bonded on the enclosure in the opening for the speaker assembly. The speaker assembly may be fitted with a plug that fits into or mates with the electrical signal contacts. A flexible membrane may be bonded to the opening for the membrane. A vent hole is drilled on an exterior wall of the enclosure surrounding the air cavity. The gas cavity may be filled through a temporary hole. If no leaks are present, the temporary hole is then sealed off. 
     For purposes of explanation, specific embodiments were described to provide a thorough understanding of the present invention. These should not be construed as limiting the scope of the invention but merely as illustrating different examples and aspects of the invention. It should be appreciated that the scope of the invention includes other embodiments not discussed in detail above. Various other modifications, changes, and variations which will be apparent to those skilled in the art may be made in the arrangement, operation, and details of the systems and methods of the present invention disclosed herein without departing from the spirit and scope of the invention as defined in the appended claims. For instance, while  FIG. 3  shows the surround  142  being in contact with and bonded to an edge of the enclosure  100  (all around the opening), thereby sealing off the opening, an alternative is to have the surround  142  first bonded to the frame  148 , and then bonding the frame  148  to the edge of the enclosure  100  (to seal off the opening). Therefore, the scope of the invention should be determined by the claims and their legal equivalents. Such equivalents include both currently known equivalents as well as equivalents developed in the future, i.e., any elements developed that perform the same function, regardless of structure. Furthermore, no element, component, or method step is intended to be dedicated to the public regardless of whether the element, component, or method step is explicitly recited in the claims.

Metadata:
Filing Date: 20101119
Publication Date: 20140701
Grant Date: 20140701
Priority Date: 20101119
Inventors: TAM CHING YU JOHN
Assignee: APPLE INC
CPC Classifications: [{"code": "H04R1/42", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04R1/42", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04R1/283", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04R1/283", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 46064408