(19) United States
`(12) Patent Application Publication (10) Pub. No.: US 2008/0226094 A1
`
`
` Rutschman (43) Pub. Date: Sep. 18, 2008
`
`US 20080226094A1
`
`(54) HEADSET HAVING WIRELESSLY LINKED
`EARPIECES
`
`(75)
`
`Inventor:
`
`_
`_
`Phillip Rutschman, Seattle, WA
`(Us)
`
`Correspondence Address:
`QUALCOMM INCORPORATED
`5775 MOREHOUSE DR-
`SAN DIEGO, CA 92121 (US)
`
`(73) Assignee:
`
`QUALCOMM Incorporated, San
`Diego, CA (US)
`
`(21) Appl. No.:
`
`12/048,038
`
`.
`(22) Filed'
`
`.
`,
`Mar 13 2008
`
`Related US. Application Data
`
`(60) Provisional application No. 60/918,252, filed on Mar.
`143 2007.
`
`Publication Classification
`
`(51)
`
`Int. Cl.
`(2006.01)
`H04B 5/00
`(2006.01)
`H04B 3/00
`(52) U.s.C1. ............................................. 381/79; 381/77
`
`ABSTRACT
`(57)
`A wireless headset includes a first earpiece and a second
`earpiece, where the first and second earpieces communicate
`with each other over a Wireless link. In some configurations,
`the first earpiece includes both a primary wireless interface
`for receiving audio from an audio source and a secondary
`wireless interface transmitting a portion of the audio to the
`second earpiece. The earpieces can incorporate Near Field
`Communication (NFC) technology to provide the wireless
`link between each other. The wireless headset can be config-
`ured to synchronize audio output at the earpieces, and can
`also include a second-earpiece detection mechanism that per-
`mits the first earpiece to be used in either a stand-alone mode,
`with audio output at only the first earpiece, or full-headset
`mode, With audio output at both earpieces when the second
`earpiece is detected Within Wireless range ofthe first earpiece.
`
`16
`
`14
`
`15
`
`SOURCE
`
`Bose Exhibit 1050
`
`Bose v. Koss
`
`

`

`Patent Application Publication
`
`Sep. 18, 2008 Sheet 1 0f 7
`
`US 2008/0226094 A1
`
`15
`
`
`
`FIG. 1
`
`15
`
`HEADSET
`
`FIG. 2
`
`

`

`Patent Application
`
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`
`Sep. 18, 2008
`
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`US 2008/0226094 A1
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`Patent Application Publication
`
`Sep. 18, 2008 Sheet 3 0f 7
`
`US 2008/0226094 A1
`
`400
`
`PRIMARY EARPIECE FUNCTIONS
`
`404
`
`PROCESSING
`
`SECONDARY
`EARPIECE
`DISCOVERY
`
`EARPIECE
`SYNCHRONIZATION
`
`AUDIO
`
`FIG. 4
`
`750
`
`RECEIVED
`TIMESTAMP
`
`ESTIMATED
` 754
`
` RECEIVER
`
`PROCESSING DELAY
`
`ADJUSTMENT
`FACTOR
`
`FIG. 8
`
`

`

`Patent Application Publication
`
`Sep. 18, 2008 Sheet 4 of 7
`
`US 2008/0226094 A1
`
`500
`
`/
`
`504
`
`Determine audio codec type
`
`Receive audio packets from audio source
`
`502
`
`506
`
`YES
`
`ranscoding
`
`Decode audio for only
`first channel
`
`requrred?
`
`
`
`508
`Decode audio into
`first and second
`channels
`
`Re-encode second
`
`channel audio using
`reduced-complexity
`codec
`
`5 l4
`
`Timestamp & buffer decoded first channel
`audio for output on primary earphone
`
`Packetize second channel audio for
`
`transmission on secondary Wireless link
`
`516
`
`518
`
`Timestamp audio packets
`
`520
`
`Transmit audio packets to secondary earphone
`on secondary Wireless link
`
`Output buffered first channel audio when
`timestamp = current time
`
`522
`
`END
`
`FIG. 5
`
`

`

`Patent Application Publication
`
`Sep. 18, 2008 Sheet 5 0f 7
`
`US 2008/0226094 A1
`
`600
`
`/
`
`BEGIN
`
`602
`
`Establish secondary Wireless
`link with primary earpiece
`
`604
`
`Synchronize local clock with
`primary earpiece clock
`
`606
`
`Receive audio packets from
`primary earplece
`
`Decode audio packets
`
`Buffer audio packets
`
`608
`
`610
`
`612
`
`Output buffered audio When
`packet time stamp = current time
`
`END
`
`FIG. 6
`
`

`

`Patent Application Publication
`
`Sep. 18, 2008 Sheet 6 of 7
`
`US 2008/0226094 A1
`
`700
`
`/
`
` 702
`
`Generate time stamp
`
`Transmit time sync packet
`containing time stamp to
`secondary earpiece
`
`704
`
`706
`
`Set secondary earpiece
`local clock according to
`time stamp
`
`FIG. 7
`
`

`

`Patent Application Publication
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`US 2008/0226094 A1
`
`Sep. 18,2008
`
`HEADSET HAVING WIRELESSLY LINKED
`EARPIECES
`
`CLAIM OR PRIORITY UNDER 35 U.S.C. §ll9
`
`[0001] The presentApplication for Patent claims priority to
`Provisional Application No. 60/918,252, entitled “Near-Field
`Communications Headset” filed Mar. 14, 2007, and assigned
`to the assignee hereof.
`
`BACKGROUND
`
`1. Field
`[0002]
`[0003] This disclosure generally relates to audio commu-
`nications, and more particularly, to audio headsets.
`[0004]
`2. Background
`[0005] Wired and wireless headsets are known. Conven-
`tional wired headsets include a wire running between an
`audio source and either one or two earpieces that are intended
`to fit on or within a user’s ears. In many cases, a wireless
`headset is simply a replacement for a wired headset. Gener-
`ally, wireless headsets substitute a wireless link for the wire
`running between the headset and audio source. Wireless
`headsets are used to provide a greater degree ofuser freedom,
`as the user is no longer tethered to the audio source by a wire.
`It is known for both wired and wireless headsets to be used
`
`with audio sources such as communication devices, e.g.,
`cordless telephones, mobile radios, personal digital assistants
`(PDAs), cellular subscriber units and the like, as well as other
`devices, such as MP3 players, stereo systems, radios, Video
`games, personal computers, laptop computers and the like.
`[0006] Known wireless headsets communicate with audio
`sources using radio frequency (RF) or infrared wireless tech-
`nology. Such wireless headset communications have been
`extended to personal wireless networks, such as the one
`defined by the Bluetooth Specification available at www.
`bluetooth.com. The Bluetooth Specification provides specific
`guidelines for providing wireless headset functionality. In
`particular, the Bluetooth Specification provides a Headset
`Profile that defines protocols and procedures for connecting a
`wireless headset to a device private network. Once config-
`ured, the headset can function as a device’s audio input and/or
`output. Thus, a particularly popular use of Bluetooth net-
`works is to provide wireless headset connectivity for cellular
`telephones, MP3 players and PDAs. In addition, the Blue-
`tooth Specification also provides the Advanced Audio Distri-
`bution Profile (A2DP) that defines protocols and procedures
`for wirelessly distributing high-quality stereo or mono audio
`over a Bluetooth network.
`
`[0007] Wireless and wired headsets are available in both
`single earpiece and dual earpiece configurations. In dual-
`earpieces headsets, the earpieces are wired together and are
`often integrated into a headband that secures an earpiece over
`or in each ear.
`
`[0008] Dual-earpiece headsets are advantageous because
`they allow playback of stereo audio and also because in some
`circumstances they allow users to fully immerse themselves
`in the audio output, while masking out noise from the imme-
`diate environment. However, known dual-earpiece headsets
`require additional wiring between earpieces and often include
`headbands, frequently making the headsets larger than some
`of contemporary audio source devices that they are intended
`to support, e.g., MP3 players, PDAs, and cellular phones. In
`addition, although dual-earpiece headsets are highly desir-
`able in some situations, they are not desirable in others. For
`
`example, in some jurisdictions, it is not permissible to operate
`motor vehicles on public roadways while wearing dual-ear-
`piece headsets.
`[0009] Thus, there is a need for an improved headset that
`allows a user to conveniently select either a single earpiece or
`dual earpiece configuration. There is also a need for an
`improved headset that provides a dual-earpiece configuration
`that eliminates the need for headbands and wiring between
`earpieces, and is therefore better scaled to the relatively small
`size of many contemporary audio devices.
`
`SUMMARY
`
`[0010] Disclosed herein is a new and improved wireless
`headset that introduces significantly greater user freedom.
`The headset described herein can be entirely wireless, with no
`wires running between the earpieces or the audio source. A
`dual-earpiece configuration of the headset does not require a
`headband or wiring between the earpieces.
`[0011] According to one aspect of the wireless headset, the
`wireless headset includes a first earpiece and a second ear-
`piece, where the first and second earpieces communicate with
`each other over a wireless link.
`
`[0012] According to another aspect ofthe wireless headset,
`the first earpiece may include both a primary wireless inter-
`face for receiving audio from an audio source and a secondary
`wireless interface for transmitting at least a portion of the
`audio to the second earpiece.
`[0013] According to a further aspect of the wireless head-
`set, a method of outputting audio at a headset includes receiv-
`ing audio at a first earpiece, transmitting the audio from the
`first earpiece to a second earpiece over a wireless link, and
`outputting the audio at the first and second earpieces.
`[0014] According to an additional aspect of the wireless
`headset, a system for outputting audio at a headset includes
`means for receiving audio at a first earpiece, means for trans-
`mitting the audio from the first earpiece to a second earpiece
`over a wireless link, and means for outputting the audio at the
`first and second earpieces.
`[0015] According to an another aspect ofthe wireless head-
`set, a computer-readable medium embodying a set of instruc-
`tions, wherein the set of instructions when executed by one or
`more processors includes a code segment for receiving audio
`at a first earpiece, a code segment for transmitting the audio
`from the first earpiece to a second earpiece over a wireless
`link, and a code segment for outputting the audio at the first
`earpiece.
`[0016] Other aspects, features, and advantages of the wire-
`less headset will be or will become apparent to one with skill
`in the art upon examination of the following figures and
`detailed description. It is intended that all such additional
`features, aspects, processes and advantages be included
`within this description and be protected by the accompanying
`claims.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`It is to be understood that the drawings are solely for
`[0017]
`purpose of illustration. Furthermore, the components in the
`figures are not necessarily to scale, emphasis instead being
`placed upon illustrating the principles of the wireless headset
`and its various aspects. In the figures, like reference numerals
`designate corresponding parts throughout the different views.
`[0018]
`FIG. 1 is a diagram illustrating a user wearing an
`exemplary wireless headset with wirelessly linked earpieces.
`
`

`

`US 2008/0226094 A1
`
`Sep. 18,2008
`
`FIG. 2 is a conceptual block diagram illustrating
`[0019]
`components of the wireless headset system of FIG. 1.
`[0020]
`FIG. 3 is a detailed block diagram illustrating spe-
`cific components of the wireless headset system of FIG. 1.
`[0021]
`FIG. 4 is a conceptual block diagram illustrating
`certain functional aspects of a primary earpiece included in
`the wireless headset.
`
`FIG. 5 is a flowchart illustrating a method of audio
`[0022]
`processing performed by the primary earpiece of the wireless
`headset.
`
`FIG. 6 is a flowchart illustrating a method of oper-
`[0023]
`ating the secondary earpiece included in the wireless headset.
`[0024]
`FIG. 7 is a flowchart illustrating a method of audio
`output clock synchronization between the primary and sec-
`ondary earpieces.
`[0025]
`FIG. 8 conceptually illustrates a process of adjust-
`ing the local audio output clock within the secondary ear-
`piece.
`FIG. 9 illustrates exemplary formats for audio and
`[0026]
`time sync packets transmitted between the primary and sec-
`ondary earpieces.
`
`DETAILED DESCRIPTION
`
`[0027] The following detailed description, which refer-
`ences to and incorporates the drawings, describes and illus-
`trates one or more specific embodiments. These embodi-
`ments, offered not to limit but only to exemplify and teach, are
`shown and described in suflicient detail to enable those
`skilled in the art to practice what is claimed. Thus, for the sake
`of brevity,
`the description may omit certain information
`known to those of skill in the art.
`
`[0028] The word “exemplary” is used throughout this dis-
`closure to mean “serving as an example, instance, or illustra-
`tion.” Any embodiment or feature described herein as “exem-
`plary” is not necessarily to be construed as preferred or
`advantageous over other embodiments or features.
`[0029] Turning now to the drawings, and in particular to
`FIG. 1, there is illustrated a user 16 wearing an exemplary
`wireless headset 11 with wirelessly linked earpieces 12, 14.
`The wireless headset 11 communicates with an audio source
`
`10 by way of a primary wireless link 20. The wireless headset
`11 and audio source 10 form a wireless headset system 15.
`[0030] The wireless headset 11 is worn as two separate
`pieces: a primary earpiece 12 and a secondary earpiece 14.
`The primary earpiece 12 communicates with the audio source
`10 via an RF or infrared primary wireless link 20, and may be
`worn either alone or separately from the secondary earpiece
`14. The secondary earpiece 14 receives audio and other infor-
`mation via a secondary wireless link with the primary ear-
`piece 12. An optional microphone on the first earpiece 12
`allows voice communication back to the audio source 10.
`
`[0031] The audio source 10 may be any device capable of
`transmitting audio signals to the headset 11 such that the
`audio represented by the audio signals can be output to a user
`from the headset 11. The audio source may be a communica-
`tion device, e.g., cordless telephone, mobile radio, personal
`digital assistant (PDA), cellular subscriber unit or the like, as
`well as another type of device, such as an MP3 player, stereo
`system, radio, video game, personal computer, laptop com-
`puter or the like.
`[0032] The audio signals transmitted between the audio
`source 10 and the headset 1 1 over the primary wireless link 20
`can represent digitized audio sampled at the industry standard
`rate of 44.1 KHZ.
`
`[0033] The headset 11 and earpieces 12, 14 can having any
`suitable physical shape and size adapted to securely fit the
`earpieces 12, 14 over or into a user’s ears. For example, the
`earpieces 12, 14 can be conventional hook-shaped earpieces
`for attaching behind a user’s earlobe and over or into the
`user’s ear canal. The headset 11 can also include a headband
`
`(not shown) connecting the earpieces 12, 14.
`[0034]
`FIG. 2 is a conceptual block diagram illustrating
`components of the wireless headset system 15 of FIG. 1. The
`primary earpiece 12 communicates with the audio source 10
`via the primary wireless link 20 and with the secondary ear-
`piece 14 by way of a secondary wireless link 22. The primary
`earpiece 12 may include a first antenna 26 for the primary
`wireless link 20 and a second antenna 28 for the secondary
`wireless link. The secondary earpiece 14 includes an antenna
`30 for communicating over the secondary wireless link 22.
`[0035] Although the primary earpiece 12 is shown as hav-
`ing separate antennas 26, 28 for the primary and secondary
`links 20, 22, respectively, one of ordinary skill in the art will
`understand that in some circumstances the primary earpiece
`12 could use a single antenna for both the primary and sec-
`ondary wireless links 20, 22.
`[0036] The primary wireless link 20 may be implemented
`using any suitable wireless communications technology,
`including short-range wireless networks such as Bluetooth,
`Wi-Fi, Ultra Wide Band (UWB), or Wireless USB links.
`Preferably, the primary wireless link 20 is a Bluetooth wire-
`less link for transporting audio, implemented in accordance
`with the Bluetooth Specification.
`[0037] The secondary wireless link 22 may use any suitable
`wireless communications technology, and is preferably
`implemented using Near Field Communication (NFC) wire-
`less devices operating in accordance with the NFC standard
`specifications, including ECMA-340, ISO/IEC 18092.
`[0038]
`In operation, the primary earpiece 12 may receive a
`stereo or monaural audio signal via the primary wireless link
`20. The primary earpiece 12 decodes the audio signal and
`renders the audio signal to its own audio transducer for output
`to the user. A copy of the audio signal or a portion thereof,
`possibly transcoded to reduce the bitrate, is also sent to the
`secondary earpiece 14 via the secondary wireless link 22. If
`the audio signal received by the primary earpiece 12 is in
`stereo, the primary earpiece 12 may render one stereo channel
`via its audio transducer, and send the other stereo channel as
`encoded audio via the secondary wireless link 22. If the
`secondary earpiece 14 is not present, the primary earpiece 14
`may instead downmix incoming stereo to monaural audio
`prior to rendering the audio to its own audio transducer.
`[0039]
`FIG. 3 is a detailed conceptual block diagram illus-
`trating specific components of the wireless headset system
`15. The primary earpiece 12 includes the antennas 26, 28, a
`primary wirclcss interface 50, a secondary wirclcss interface
`52, a processor 54, a memory 56, an audio output buffer 58, an
`audio transmit (Tx) buffer 60, audio output circuitry 62,
`microphone input circuitry 64, a speaker 68, and a micro-
`phone 66. The primary earpiece 12 also includes a battery 70
`and a battery charger circuit 72.
`[0040] The primary wireless interface 50 provides two-way
`wireless communications with the audio source 10. Prefer-
`
`ably, the primary wireless interface 50 includes a commer-
`cially-available Bluetooth module that provides at least a
`Bluetooth core system consisting of a Bluetooth RF trans-
`
`

`

`US 2008/0226094 A1
`
`Sep. 18,2008
`
`ceiver, baseband processor, protocol stack, as well as hard-
`ware and software interfaces for connecting the module to the
`processor 54.
`[0041] The processor 54 controls the overall operation of
`the primary earpiece 12 and certain components contained
`therein. The processor 54 can be any suitable processing
`device for executing programming instructions stored in the
`memory 56 to cause the primary earpiece 12 to perform its
`functions and processes as described herein. For example, the
`processor 54 can be a microprocessor, such as an ARM7,
`digital signal processor (DSP), one or more application spe-
`cific integrated circuits (ASle), field programmable gate
`arrays
`(FPGAs), complex programmable logic devices
`(CPLDs), discrete logic, software, hardware, firmware or any
`suitable combination thereof.
`
`[0042] The memory 56 is any suitable memory device for
`storing programming instructions and data executed and used
`by the processor 54.
`[0043] The audio output buffer 58 is any suitable memory
`device for temporarily storing digitized audio before it is
`transferred to the audio output circuitry 62 for rendering at the
`primary earpiece 12. The audio output buffer 58 is controlled
`by the processor 54 and buffers time-stamped audio packets
`awaiting output at the primary earpiece 12. Although shown
`as a separate component ofthe primary earpiece 12, the audio
`output buffer 58 may be included in the memory 56.
`[0044] The audio output circuitry 62 includes a digital-to-
`analog converter (DAC) 70 and an audio amplifier 72. The
`DAC 70 converts digitized audio into an analog audio signal.
`The analog audio signal is then amplified by the audio ampli-
`fier 72 to drive the speaker 68. The audio output circuitry 62
`is preferably implemented using commercially-available,
`off-the-shelf components.
`[0045] The speaker 68 is any suitable audio transducer for
`converting the electronic signals output from the amplifier 72
`into sound.
`
`[0046] The microphone (MIC) 66 is any suitable micro-
`phone device for converting sound into electronic signals.
`The microphone 66 and speaker 68 may be combined into a
`single device in some configurations of the primary earpiece
`12.
`
`[0047] The microphone input circuitry 64 processing elec-
`tronic signals received from the microphone 66. The micro-
`phone input circuitry 64 includes an analog-to-digital con-
`verter (ADC) 74 and a noise reduction and echo cancellation
`circuit (NREC) 76. The ADC 74 converts analog signals from
`the microphone into digital signal that are then processed by
`the NREC 76. The NREC 76 is employed to reduce undesir-
`able audio artifacts for communications and voice control
`
`applications. The microphone input circuitry 64, the ADC 74
`and NREC 76 may be implemented using commercially-
`available hardware, software, firmware, or any suitable com-
`bination thereof.
`
`[0048] The microphone 66 may send audio data over the
`primary wireless link 20 to the audio source 10. The device
`receiving the microphone signal need not in general be the
`same audio source device as is sending the audio to the
`primary earpiece 12.
`[0049] The audio Tx buffer 60 is any suitable memory
`device for temporarily storing digitized audio before it is
`transmitted over the secondary wireless interface 52 for ren-
`dering at the secondary earpiece 14. The audio Tx buffer 60 is
`controlled by the processor 54 and buffers time-stamped
`audio packets awaiting transmission to the secondary ear-
`
`piece 14. Although shown as a separate component of the
`primary earpiece 12, the audio Tx buffer 60 may be included
`in the memory 56.
`[0050] The secondary wireless interface 52 provides two-
`way wireless communications with the secondary earpiece
`14. Preferably, the secondary wireless interface 52 includes a
`commercially-available NFC module that provides at least an
`NFC RF transceiver, baseband processor, protocol stack, as
`well as hardware and software interfaces for connecting the
`NFC module to the processor 54.
`[0051] The battery 70 can be a replaceable, rechargeable
`battery for powering the primary earpiece 12. The battery
`charger circuit 72 may be a commercially-available battery
`charger circuit having an external jack that permits the battery
`70 to be recharged using an AC wall adapter. The battery
`charger circuit 72 may be controlled by the processor 54.
`[0052] The secondary earpiece 14 includes the antenna 30,
`a secondary wireless interface 100, a processor 102, a
`memory 104, an audio buffer 106, audio output circuitry 108,
`and a speaker 110. The secondary earpiece 14 also includes a
`battery 116 and a battery charger circuit 118.
`[0053] The processor 102 controls the overall operation of
`the secondary earpiece 14 and certain components contained
`therein. The processor 102 can be any suitable processing
`device for executing programming instructions stored in the
`memory 104 to cause the secondary earpiece 14 to perform its
`functions and processes as described herein. For example, the
`processor 102 can be a microprocessor, such as an ARM7,
`digital signal processor (DSP), one or more application spe-
`cific integrated circuits (ASle), field programmable gate
`arrays (FPGAs), complex programmable logic devices
`(CPLDs), discrete logic, software, hardware, firmware or any
`suitable combination thereof.
`
`[0054] The memory 104 is any suitable memory device for
`storing programming instructions and data executed and used
`by the processor 102.
`[0055] The secondary wireless interface 100 provides two-
`way wireless communications with the primary earpiece 12.
`Preferably, the secondary wireless interface 100 includes a
`commercially-available NFC module that provides at least an
`NFC RF transceiver, baseband processor, protocol stack, as
`well as hardware and software interfaces for connecting the
`NFC module to the processor 102.
`[0056] The audio buffer 106 is any suitable memory device
`for temporarily storing digitized audio before it is transferred
`to the audio output circuitry 108 for rendering at the second-
`ary earpiece 14. The audio buffer 106 is controlled by the
`processor 102 and buffers time-stamped audio packets
`received at the secondary wireless interface 100 and awaiting
`output at the secondary earpiece 14. Although shown as a
`separate component of the secondary earpiece 14, the audio
`buffer 106 may be included in the memory 104.
`[0057] The audio output circuitry 108 includes a digital-to-
`analog convcrtcr (DAC) 112 and an audio amplificr 114. The
`DAC 112 converts digitized audio into an analog audio signal.
`The analog audio signal is then amplified by the audio ampli-
`fier 114 to drive the speaker 110. The audio output circuitry
`108 is preferably implemented using commercially-avail-
`able, off—the-shelf components.
`[0058] The speaker 110 is any suitable audio transducer for
`converting the electronic signals output from the amplifier
`114 into sound.
`
`[0059] The battery 116 can be a replaceable, rechargeable
`battery for powering the secondary earpiece 14. The battery
`
`

`

`US 2008/0226094 A1
`
`Sep. 18,2008
`
`charger circuit 118 may be a commercially-available battery
`charger circuit having an external jack that permits the battery
`116 to be recharged using an AC wall adapter. The battery
`charger circuit 118 may be controlled by the processor 102.
`[0060]
`FIG. 4 is a conceptual block diagram illustrating
`certain functional aspects of a primary earpiece 12. The pri-
`mary earpiece functions 400 generally include, but are not
`limited to, a secondary earpiece discovery function 402, an
`earpiece synchronization function 404, and an audio process-
`ing function 406.
`[0061] The secondary earpiece discovery function 402
`involves detecting the presence of the secondary wireless
`earpiece 14 when it is within range of the first earpiece 12
`through the secondary wireless link 22. Upon detecting the
`second earpiece 14, the first earpiece proceeds to initiate and
`establish the secondary wireless link 22 with the secondary
`earpiece 14 so that audio can be output at the secondary
`earpiece 14. The detection and link initiation protocols and
`procedures are described by the NFC standard specification.
`[0062] Each earpiece 12, 14 can store a unique identifica-
`tion number in its respective memory 56, 104 so that headset
`earpieces can be paired together to only recognize and com-
`municate with each other.
`
`[0063] The primary earpiece 12 can be adaptively config-
`ured to operate in a single-earpiece mode (stand-alone mode)
`when the secondary earpiece 14 is not within range of the
`secondary wireless link 22 and in a dual-earpiece mode (full-
`headset mode) when the secondary earpiece 14 is within
`range. In single-earpiece mode, the primary earpiece 12 does
`not process audio for transmission to the secondary earpiece
`14 and down-mixes any stereo input for output only at the
`primary earpiece 12. This reduces that power consumption of
`the primary earpiece 12.
`[0064]
`In dual-earpiece mode, the primary earpiece pro-
`cesses and transmits audio and time synchronization data to
`the secondary earpiece 14. The primary earpiece 12 can
`switch from the single-earpiece mode to the dual-earpiece
`mode upon detecting the presence of the secondary earpiece
`14 with wireless range, and can also switch from the dual-
`earpiece mode to the single-earpiece mode upon determining
`that the secondary earpiece 14 has moved out of wireless
`range.
`Software or firmware stored in the memory 56 and
`[0065]
`executed by the processor 54 can implement the earpiece
`mode functionality of the primary earpiece 12. The software/
`firmware can configure the processor 54 to actively monitor
`the secondary wireless interface 52 to detect the presence or
`absence of the secondary earpiece 14 on the secondary link
`22, and to switch between the single-earpiece and dual-ear-
`piece modes are described immediately above.
`[0066] The earpiece synchronization function 402 involves
`synchronizing local clocks in the primary and secondary ear-
`pieces 12, 14 so as to synchronize the audio output at both
`earpieces 12, 14. This ensures that the separate rendering of
`the audio at the different earpieces 12, 14 retains inter-chan-
`nel synchronization. Both earpieces 12, 14 maintain separate
`audio output clocks. These clocks are used to determine when
`to output chucks of audio from the earpieces 12, 14 at the
`speakers 68, 110. The audio output clocks have approxi-
`mately the same frequency and each has an absolute current
`time value. The earpiece synchronization function 402 peri-
`odically adjusts the current time value of the secondary ear-
`piece audio output clock so that it is at least approximately
`equal to the current time value of the primary earpiece audio
`
`output clock. The earpiece synchronization function 402 can
`also control the frequency of the local audio output clocks.
`FIGS. 7 and 8 describe methods for synchronizing the ear-
`piece audio output clocks.
`[0067] The audio processing function 406 involves the
`reception, transcoding (if necessary), re-transmission, and
`playback of audio received from the audio source 10. FIG. 5
`describes a method of performing the audio processing func-
`tion 406 of the primary earpiece 12. FIG. 6 describes audio
`processing carried out by the secondary earpiece 14.
`[0068]
`FIG. 5 is a flowchart 500 illustrating a method of
`audio process performed by the primary earpiece 12 of the
`wireless headset 11. Generally, the method is performed
`under the control ofthe processor 54, coordinating operations
`of the various components of the primary earpiece 12.
`[0069]
`In step 502, a Bluetooth streaming audio connection
`is established between the audio source 10 and the primary
`earpiece 12, as described in the A2DP specification. During
`this step, the audio codec type for incoming audio from the
`audio source 10 is determined. Using Bluetooth as the pri-
`mary wireless link 20, the audio source 10 and the primary
`earpiece 12 can negotiate and determine the codec type using
`standard A2DP protocols and procedures.
`[0070]
`In step 504, after the Bluetooth streaming audio
`connection is established, audio packets are transmitted from
`the audio source 10 over the primary wireless link 20 and
`received by the primary wireless interface 50 of the primary
`earpiece 12. Generally, the audio packets include digitized
`audio that is encoded using the negotiated codec. Each audio
`packet represents a predetermined duration of sound, e. g., 20
`milliseconds, that is to be output at the headset 11. The audio
`packets can be formatted according to the A2DP profile,
`including one or more frames of encoded audio. The audio
`can be encoded using any suitable audio codec, including but
`not limited to SBC, MPEG-1 audio, MPEG-2 audio.
`[0071]
`In decision step 506, the processor 54 determines
`whether the incoming audio should be transcoded prior to
`re-transmission on the secondary wireless link 22. Generally,
`if the codec type used on the primary wireless link 20 is
`relatively complex, e.g., MPEG-1, the incoming audio is
`transcoded from the relatively complex code to a simpler
`code using a reduced-complexity codec, such as a Bluetooth
`sub-band codec (SBC).
`[0072]
`Ifthe audio packets are to be transcoded, the incom-
`ing packets are first fully decoded into first and second audio
`channels (step 508). The second audio channel, which is
`destined for the secondary earpiece 14, is re-encoded using a
`reduced-complexity codec (step 510). The reduced-complex-
`ity codec can be implemented by software running on the
`processor 54.
`[0073]
`If the audio packets are not transcoded, the audio
`packets are only partially decoded. Specifically, only the first
`audio channel is decoded for playback at the primary earpiece
`12 (step 512). The second channel audio is not dccodcd and is
`simply re-packetized for transmission to the secondary ear-
`piece 14 over the secondary wireless link 22.
`[0074]
`In step 514, the decoded first audio channel is buff-
`ered in the audio output buffer 58 for subsequent output at the
`speaker 68 of the primary earpiece 12. Each packet of
`decoded first channel audio is time-stamped so that it can be
`output in synchronization with audio output at the secondary
`earpiece 14.
`[0075]
`In step 516, the processor 54 packetizes the second
`audio channel into one or more audio packets for transmission
`
`

`

`US 2008/0226094 A1
`
`Sep. 18, 2008
`
`to the secondary earpiece 14 by way ofthe secondary wireless
`link 22. FIG. 9 depicts an example format for the audio
`packets 800 transmitted on the secondary wireless link 22.
`The audio packets are preferably formatted for transmission
`over an NFC link, according to the NFC Interface and Proto-
`col (NFCIP-l) specification, ISO/IEC 18092.
`[0076]
`In step 518, a time stamp is included in each of the
`audio packets. The time stamps indicate the times at which the
`secondary earpiece 14 will output the audio contained in the
`packets. The time stamps are useful for synchronizing the
`audio output of the primary and secondary earpieces 12, 14.
`[0077]
`In step 520, the primary earpiece 12 transmits the
`time-stamped audio packets over the secondary wireless l