Patent Publication Number: US-2006018488-A1

Title: Bone conduction systems and methods

Description:
RELATED APPLICATIONS  
      This application is a Continuation-in-Part of U.S. patent application Ser. No. 10/803,309, titled “UNDERWATER ENTERTAINMENT SYSTEM,” filed Mar. 18, 2004. The U.S. patent application Ser. No. 10/803,309, titled “UNDERWATER ENTERTAINMENT SYSTEM,” filed Mar. 18, 2004, claims priority under 35 U.S.C. § 119(e) from the co-pending U.S. provisional patent application Ser. No. 60/493,667, filed on Sep. 7, 2003, and titled “UNDERWATER DIGITAL MUSIC PLAYER.” The U.S. patent application Ser. No. 10/803,309, titled “UNDERWATER ENTERTAINMENT SYSTEM,” filed Mar. 18, 2004 and provisional patent application Ser. No. 60/493,667, filed on Sep. 7, 2003, and titled “UNDERWATER DIGITAL MUSIC PLAYER” are both hereby incorporated by reference. 
    
    
     FIELD OF THE INVENTION  
      This invention relates to systems for and methods of transmitting content data using bone conduction. More particularly, this invention relates to systems for and methods of transmitting audible music signals, two-way communication signals and timing signals using bone conduction.  
     BACKGROUND  
      Content data, such as music and voice communications, are often transmitted using audio signals that are made audible with a speaker or a headset having built-in speakers. There are a number of situations where it would be useful to transmit and/or receive content data where traditional speakers are either not useful or are unsafe. For example, when a person is in an aquatic environment, speakers do not perform well or can not be used at all. Also, when a person is performing an activity, such as running, skateboarding, snow skiing, water skiing, riding a bicycle or a motorcycle, it is not safe to listen to contend date using a headset with speakers, because the headset can prevent the user from hearing other sounds in the environment.  
      What is needed is a system for transmitting content data by means which can be used in aquatic environments and/or which can allow a user to hear other sounds in the environment while receiving the content data.  
     SUMMARY OF THE INVENTION  
      The present invention is directed to a system for and a method of communicating content data to a user through bone conduction. The content data can include radio content data, such as FM and AM radio content data, or radio packet content data and two-way radio content data, such as is typically used for portable communication devices including, but not limited to, cellular phones, walkie talkies and the like. Bone conduction and bone conduction output data herein generally refer to the vibrations that are generated by a suitable device that has a surface in contact with a bony portion of a user, most notably, a bony portion of the user&#39;s head. The vibrations are transmitted through the bones and generate sound or an audible signal from within one or more internal cavities of the user&#39;s head, such as an inner ear canal.  
      In accordance with the embodiment of the of the invention, a system comprises headgear for coupling to a user&#39;s head. The headgear can be a headband, a visor, a hat, a helmet, a pair of goggles, a pair of glasses or combinations thereof. The system includes a control unit with a receiver configured to receive wireless content data, such as described above. The system also includes a converter coupled to the headgear for converting received wireless content data into bone conduction output data. The system also preferably includes a transmitter coupled to the headgear for transmitting wireless communication signals from sound. For example, the transmitter includes a radio transmitter coupled to a microphone, such that a user can speak into the microphone to generate or send outgoing communication signals to a second user wearing a similar system or other compatible device.  
      In accordance with further embodiments of the invention, the system includes a player unit for playing recorded or stored content data through the converting means, such as the bone conduction speaker. The player unit is preferably configured for playing digitally recorded or digitally stored content data in any suitable format, such as MP3 format (MPEG-1 Audio Layer-3 compressed format). The player unit can also be configured to record content data from a live content data stream. Further, the player unit can be configured to couple to an Internet-enabling device to download content data therefrom using, for example, a USB (Universal Serial Bus) connection or a wireless connection. Also, the player unit be internet enabled, such that the player unit can download content data directly over the internet. The player unit can also be network enabled, such that the player unit can interface with other electronic devices. For example, the player unit can employ “Blue Tooth” technology or any other suitable network technology.  
      In accordance with the preferred embodiment of the invention, a system includes bone conduction speakers with diaphragms that are placed in intimate contact with a bony portions of a user&#39;s head to generate audible sounds within one or more cavities of the users&#39; head, such as described above. The diaphragms can be sealed diaphragms, such that the bone conduction speakers are suitable for use in aquatic environments. Preferably the diaphragms are capable of contouring to surfaces of the bony portions of the user&#39;s head, such that a large surface area of the diaphragms are in contact with the bony portions of the user&#39;s head. Further, the bone conduction speakers can include pressure compensators, such that the pressure differential across moving parts of the bone conduction speakers remains sufficiently equal to allow the speakers to operate at a range of different pressures.  
      In accordance with the embodiments of the invention, a system comprises a timer unit for generating timing signals at a selectable frequency. The timing signals are then converted to timing outputs transmitted to a user through one or more bone conduction speakers, such as described above.  
      In accordance with yet further embodiments of the invention a system is configured for two-way communication. The system comprises a transceiver for receiving incoming wireless communication signals and transmitting outgoing wireless communication signals. Preferably, the transceiver receives and transmits radio packet content data used in cellular phones. The system also includes one or more bone conduction speakers for converting the incoming wireless communication signals into bone conduction signals, such as described above. The system also includes an input device, preferably a microphone, for converting sound into the outgoing communication signals. The bone conduction speakers and microphone can be integrated with or configured to couple to any suitable headgear such as a headband, a visor, a hat, a helmet, a pair of goggles or a pair of glasses. The system can also includes a digital player unit for playing and recording digital music, such as described above. 
    
    
     BRIEF DESCRIPTION OF FIGURES  
       FIG. 1  shows a system for transmitting content date using bone conduction, in accordance with the embodiments of the invention.  
       FIG. 2A  shows a system configured to secure to a user&#39;s head and for transmitting content data using bone conduction, in accordance with the embodiments of the invention.  
       FIG. 2B  shows a helmet with a built-in bone conduction system, in accordance with the embodiments of the invention.  
       FIG. 2C  shows a pair of glasses with a built-in bone conduction system, in accordance with the embodiments of the invention.  
       FIG. 3A  shows a touch control architecture for inputting system functions into a system using bone conduction, in accordance with the embodiments of the invention.  
       FIG. 3B  shows an entertainment system configured to couple to a strap for securing the bone conduction system to a portion of a user&#39;s body, in accordance with the embodiments of the invention.  
      FIGS.  4 A-B show exploded views of a bone conduction system, in accordance with the embodiments of the invention.  
       FIG. 5  shows a speaker-earplug for transmitting audio output signals from an entertainment system to a user&#39;s ear, while the user is in a water environment or submersed in water, in accordance with the embodiments of the invention.  
       FIG. 6A  shows a sealed membrane bone conduction speaker unit for transmitting bone conduction output signals through a bony portion of a user&#39;s head, in accordance with the embodiments of the invention.  
       FIG. 6B  shows a sealed membrane bone conduction speaker unit with a pressure compensator, in accordance with the embodiments of the invention.  
       FIG. 7  shows a headband with a built-in bone conduction system for transmitting content data to a user using bone conduction, in accordance with the embodiments of the invention.  
      FIGS.  8 A-B show a bone conduction system with a timer circuit, in accordance with the embodiments of the invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
      Referring to  FIG. 1 , the present invention is directed to a system  100  comprising a control unit  102  that can include a water resistant housing  101 . Preferably, control unit  102  includes media player unit  115  and any necessary circuitry for receiving, transmitting, storing and playing content data. For example, necessary circuitry can include a digital processor unit, a digital signal processor (DSP), a digital-to-analog converter, data storage circuitry, software, a data storage unit, an amplifier, a power source, a transmitter, a receiver, etc. The control unit  102  can also include a USB connection or a wireless connection, slots for reading removable data storage devices or any other means known in the art for inputting content data. Also, the control unit  102  be Internet-enabled, such that the player unit  115  can download content data directly over the Internet. The control unit  102  can also be network enabled, such that control unit  102  can interface with other electronic devices.  
      In accordance with yet further embodiments of the invention, the control unit  102  includes a receiver unit  105  for receiving wireless content data or communication signals in real time. The system  100  can also include a transmitting unit  105 ′ for transmitting wireless content data or communication signals from the control unit  102  to a compatible receiving device. Preferably, the control unit  102  also includes an external or an internal antenna  117  for receiving wireless content data or communication signals. Wireless content data or communication signals can be generated or input using any suitable input means, including but not limited to input keys, a graphical user interface and/or a microphone, such as described below.  
      Still referring to  FIG. 1 , the system  100  includes an output or converting means  108  configured for delivering the content data received from the control unit  102  or being played from the media player unit  115  into a user friendly form. Preferably the output or converting means  108  includes pair of bone conduction speakers  109  and  109 ′ that can be permanently fixed to, or detachably coupled to, the control unit  102  through electrical connections  107  and  107 ′, respectively. The bone conduction speakers  109  and  109 ′ preferably include contact diaphragms that are placed against bony portions of a user&#39;s head to deliver the content data to the user via vibrations through bones in the users&#39; head. The system  100  can include any suitable attaching means  103  and  103 ′ for attaching the system  100  to a portion or of the user&#39;s body, an article and/or vehicle.  
      Referring now to  FIG. 2A , a system  200  includes a control unit  201 , such as described above with reference to  FIG. 1 . The control unit  201  preferably includes a radio transceiver for receiving and transmitting radio communication signals, in any suitable format including radio packet data. The system  200 , also includes a headband  203  with one or more support structures  207  for supporting one or more corresponding bone conduction speakers  209 . The headband  203  is preferably configured to hold the one or more bone conduction speakers  209  against a bony portion of a user&#39;s head  213 . The head band  203  can also be configured to hold or support the control unit  201 . The control unit  201  and/or the bone conduction speakers  209  can be configured to detachably couple to the headband  203  through any suitable attachment means including clips, snaps, brackets, two-part fabric or any combination thereof.  
      Still referring to  FIG. 2A , the system  200  also preferably includes an input means  202 , such as a microphone, configured for inputting communication signals into the control unit  201  from sound or voice. The communication signals that are input through the input means  202  can be recorded or transmitted to a compatible receiving device (not shown). As described above, the control unit  201  can also include a player unit, for playing recorded or stored content data and a memory unit for recording and storing content data. To improve the quality of the bone conduction output signals from the one or more bone conduction speakers  209 , sound filter ear plugs  215  that block noise or selected frequencies of noise can be employed.  
       FIG. 2B  shows a system  250  that includes a helmet  251  with a pair of bone conduction speakers  255  and  257 . The bone conduction speakers  255  and  257  are permanently or detachably coupled to the inside of the helmet  251 , such that the bone conduction speakers  255  and  257  are held in contact with a portion of a user&#39;s head while the user is wearing the helmet  251 . The bone conduction speakers  255  and  257  preferably include diaphragms for generating audible sounds through bony portions of the user&#39;s head, as described above.  
      In accordance with the embodiments of the invention, the system  250  also includes a microphone  253 , wherein the bone conduction speakers  255  and  257  and the microphone  253  serve as two-way communication headset  256  suitable for delivering and generating two-way radio communication signals.  
      Still referring to  FIG. 2B , the system  250  also includes a control unit  259  that includes a transceiver  263 , an antenna  271  and a battery  267  for receiving radio communication signals and delivering communication signals to the user through the bone conduction speakers  255  and  257  and for transmitting radio communication signals generated by the user&#39;s voice through the microphone  253 . The control unit  259  can be electrically coupled to the headset  256  through one or more wires  260  and a connector  261 . The connector  261  can be configured to allow the headset  256  to be detectably coupled to the control unit  259 . In accordance with further embodiments of the invention, the headset  256  and the control unit  259  are configured to couple through a wireless connection. The control unit  259  can be configured to couple to the helmet  251 , a portion of a vehicle, such as a motorcycle, or a portion of the user&#39;s body through any suitable means. Further, the control unit  259  can include a media player unit  265  for playing recorded or stored media content data, such as described above.  
       FIG. 2C  shows a system  275  that includes a pair of glasses  282  with built-in bone conduction speakers  281  and  283 , in accordance with the embodiments of the invention. The bone conduction speakers  282  and  283  are preferably molded or otherwise coupled to the frame of the pair of glasses  281 . Wires  284  can also be molded into the frame of the pair of glasses  282  to provide the necessary electrical connections to deliver content data to the user through the bone conduction speakers  281  and  283 . Preferably, the bone conduction speakers  281  and  283  are held in contact with bony portions of the user&#39;s head while the user is wearing the pair of glasses  282  and the bone conduction speakers  281  and  283  preferably include diaphragms (not shown) for generating audible sounds through the bony portions of the user&#39;s head, as described above. The diaphragms are preferably flexible and resilient, such that the diaphragms can conform to contours of the bony portions of the user&#39;s head for efficient transmission of bone conduction signals.  
      Still referring to  FIG. 2C , the system  275  also includes a control unit  290  that includes a receiver  293 , an antenna  291  and a battery  295  for receiving radio communication signals delivered to the user through the bone conduction speakers  281  and  283 . The control unit  290  can be electrically coupled to the bone conduction speakers  281  and  283  through one or more wires  287  and a connector  288 . The connector  288  can be configured to allow the bone conduction speakers  281  and  283 , along with the pair of glasses  282 , to detectably couple to the control unit  290 . In accordance with further embodiments of the invention, the bone conduction speakers  281  and  283  and the control unit  290  are configured to couple through a wireless connection. The control unit  290  can be configured to couple to the pair of glasses  282 , a portion of a vehicle, such a bicycle, or a portion of the user&#39;s body through any suitable means. Further, the control unit  290  can include a media player unit  297  for playing recorded or stored media content data, such as described above.  
       FIG. 3  shows a schematic of control unit  300  with a media player unit, in accordance with the embodiments of the invention. The control unit  300  can comprise a number of controls  303 ,  305 ,  307  and  309 , which allow a user to input operational commands such as changing an output volume, selecting a media file to be played, turning the media player unit on and off, resetting the media player unit, tuning a radio receiver, to name a few. The touch control buttons  303 ,  305 ,  307  and  309  can be used in conjunction with firmware that allows the control unit  300  to be programmed in any number of different ways, such as to play a preferred play list of content data, to turn on or turn off at a selected time, to name a few. The control buttons  303 ,  305 ,  307  and  309  and/or the control unit  300  can also include one or more display lights  311  and  311 ′ that provide an indication of the operational state of the control unit  300 . For example, the display lights  311  and  311 ′ can indicate when the control unit  300  is on, when the control unit  300  is playing prerecorded or stored content data and the like. The display lights  311  and  311 ′ are preferably LED display lights. The control unit  300  can also include a LCD displays and a number pad for dialing numbers and/or sending text messages from the control unit  300 . A bone conduction system in accordance the embodiments of the invention can have any number of different control buttons and/or display features that include LED arrays and/or LCDs and can also include an audible indicator, such as an alarm that signals a time or status of the system.  
       FIG. 3B  shows a control unit  350  configured to couple to a portion of a user&#39;s body, in accordance with the embodiments of the invention. The control unit  350  can include a MP3 player, a radio receiver, a transmitter, an antenna, a data storage unit and a battery that is housed within a water resistant housing  351 . Preferably, the water resistant housing  351  includes a touch control panel  353  with touch control buttons for inputting control commands to operate the control unit  350 , such as described with reference to  FIG. 3A . The control unit  350  can also include one or more attachment features  357  and  357 ′ coupled to the water resistant housing  351 . The attachment features  357  and  357 ′ can be configured to attach to a strap (not shown), which can then be used to secure the control unit  350  to a portion of a user&#39;s body.  
      Still referring to  FIG. 3B , the water resistant housing  351  and the attachment features  357  and  357 ′ are preferably formed from molded plastic or rubber. The control unit  350  has at least one output connection  355  for connecting to one or more bone conduction speakers and or a headset with one or more bone conduction speakers, such as described with reference to  FIGS. 2B-2C , respectively. Also, the control unit  350  is preferably configured with an input port for connecting to a data source, as described below with reference to FIGS.  4 A-B.  
      FIGS.  4 A-B show exploded views  400  and  450  of a control unit, in accordance with the embodiments of the invention.  FIG. 4A  shows a top exploded view  400  and  FIG. 4B  shows a bottom exploded view  450 , respectively. The control unit can be formed from a top control pad  401  with touch controls for inputting control commands, as described above with reference to FIGS.  3 A-B. Next, the control unit can include an upper casing  403  that fits into a lower casing  407  to form a housing structure for housing an electronic unit  405 . The electronic unit  405  preferably includes all of the necessary circuitry, memory, amplifiers, power source and processing capabilities required for transmitting radio signals, receiving radio signals, downloading content data, storing content data and playing content data. Next, the control unit has a strap casing  409  that fits to the housing structure formed from the upper casing  403  and the lower casing  407  and preferably provides a means for securing the housing portion to a user&#39;s body.  
      Still referring to FIGS.  4 A-B, the lower casing  407  and the strap casing  409  can have apertures  406  and  408 , respectively, that form an input port for inputting data files to the electronic unit  405 . The input port can be covered with a cap structure  411  that is secured to the strap casing  409  through a rivet member  413 . All of the components  401 ,  403 ,  405 ,  407 ,  409 ,  411  and  413  that combine to form the control unit can be secured, fitted or interlocked together using any number of securing mechanisms including, but not limited to, rubber rivets, glue and the like. Furthermore, the control unit of the present invention can include any number of gaskets or seals required to provide durability and/or water resistance required for the intended use.  
       FIG. 5  shows a water resistant ear plug/speaker unit  500  that can be used for outputting a representation of audio signals generated by a player unit, such as described above. The water resistant ear plug/speaker unit  500  comprises a housing  501  for housing electronic components of the ear plug/speaker unit  500 . The ear plug/speaker unit  500  preferably comprises a nozzle or cone structure  513  for inserting into a user&#39;s&#39;s ear and delivering sound to the user&#39;s ear therefrom. An outer portion  507  of the nozzle or cone structure  513  can be formed from a soft malleable material that allows the ear plug/speaker unit  500  to adapt to different ear shapes. The cone structure  513  can be sealed to the outer portion  507  through a rubber gasket  511 . Within the housing  501 , there is a fenestrated member  509  that allows water to drain from a cavity between the fenestrated member  509  and a transducer  503 . Preferably, the transducer  503  has a sealed membrane structure  505  that oscillates to generate sound from audio signals received by a media player unit through a water resistant electrical connection  515 .  
       FIG. 6A  shows a bone conduction speaker unit  600  for providing bone conduction transmission of content data generated by a control unit, in accordance with a preferred embodiment of the invention. The bone conduction speaker unit  600  comprises a housing  601  for housing electronic components of the bone conduction speaker unit  600 . The bone conduction speaker unit  600  preferably comprises a transducer  603  with an oscillating diaphragm  607  that vibrates in response to content data signals processed by the control unit, such as described in detail above with reference to FIGS.  1 ,  2 A- 2 C,  3 A- 3 B and  4 A-B, and transmitted through a water resistant electrical connection  615  or wireless connection. The bone conduction speaker unit  600  is preferably water resistant and includes a sealed membrane  611  that is configured to be placed on and secured against a bony portion of the user&#39;s head to transfer vibrations therefrom and which generate signals that are audible from the inner portion of the user&#39;s ears. The bone conduction speaker  600  can include a coupling structure  606  that is configured to facilitate mechanical transmission of vibrations from the oscillating diaphragm  607  to the sealed membrane  611 . Alternatively, the oscillating diaphragm  607  can be sealed and placed in direct contact with a bony portion of the user&#39;s head to transmit sound therefrom. As stated above, the bone conduction speaker  600  can be secured to bony portions of a user&#39;s head using any number of means including, but not limited to, brackets, clips and straps that are either part of the system or that are separate from the system. Preferably, the bone conduction speaker  600  can be secured to bony portions of a user&#39;s head through headgear, such as a headband, a visor, a hat, a helmet, a pair of goggles, a pair of glasses and combinations thereof.  
       FIG. 6B  shows a bone conduction speaker unit  650  for providing bone conduction transmission of content data generated by a control unit, in accordance with further embodiments of the invention. The bone conduction speaker  650  comprises a housing  671  for housing electronic components of the bone conduction speaker unit  650 , such as a transducer  653 , an oscillating diaphragm  657  and a coupling structure  656 , such as described above with reference to  FIG. 6A . The bone conduction speaker unit  650  preferably includes a sealed diaphragm that allows the bone conduction speaker unit  650  to be used under water or in aquatic environments and can conform to contours of the user&#39;s head. The bone conduction speaker unit  650  also preferably includes a pressure compensator  675  for reducing the pressure deferential between the outside  655  of the housing  671  and the inside  670  of the housing  671 . This allows moving parts, such as the oscillating diaphragm  657 , the coupling structure  656  and a sealed diaphragm  651 , to operate at greater depths of water. Without the pressure compensator  675 , in deep water the pressure differential across the moving parts of the bone conduction speaker unit  650  can become so great that the bone conduction speaker unit  650  fails to function properly. The pressure compensator  675  can also help equalize the pressure differential between the outside  655  of the speaker housing  671  and the inside  670  of the speaker housing  671  at low pressure conditions, such as at high altitudes, and thus help the bone conduction speaker unit  650  maintain consistent performance in a variety of pressure conditions.  
      The pressure compensator  675  can include a movable pressure diaphragm  661  that can be displaced, as indicated by the arrow  677 , through compression regions  663  and  663 ′ in response to pressures changes. The pressure compensator  675  can also include a controller arm  669  for controlling or regulating the displacement of the pressure diaphragm  661  in response to the pressure changes. Details of pressure compensators are further described in U.S. Pat. No. 5,678,541, titled “BREATHING REGULATOR APPARATUS HAVING AUTOMATIC FLOW CONTROL,” the contents of which are hereby incorporated by reference.  
      In operation, the sealed membrane  651  of the bone conduction speaker unit  650  is placed on and secured against a bony portion of the user&#39;s head. The bone conduction speaker unit  650  generates vibrations from content data signals processed by a control unit, such as described in detail above, and transmitted through a water resistant electrical connection  655  or wireless connection. The vibrations from the sealed diaphragm  651  are transferred to the bony portion of the user&#39;s head to generate audible signals at the inner portion of the user&#39;s ears. As the bone conduction speaker unit  650  is operated through a range of pressures, the pressure diaphragm  661  moves, as indicated by the arrow  677 , to reduce the pressure differential between the outside  655  and the inside  670  of the housing  671 .  
       FIG. 7  illustrates a system  700  that is configured to attach to a user&#39;s head  702 , in accordance with further embodiments of the invention. The system  700  is configured to wrap around a forehead portion of the user&#39;s head  702  through a flexible strap  701 . The system  700  comprises a control unit  703  with all of the necessary components to receive, store and play content data files and/or receive and transmit radio communication signals, including a processor, a memory unit, a power source, an amplifier circuit, a radio transmitter, a radio receiver and an antenna, such as described in detail above. Also, the system  700  is preferably configured with controls and/or displays  711  and/or an input port  713 , also described above. In accordance with this embodiment, the system  700  comprises water resistant bone conduction speakers  705  and  707  that are built into the strap  701  and housed in water resistant housing structures on the strap  701 . The water resistant bone conduction speakers  705  and  707  comprise transducers  725  and  727  with sealed membranes  721  and  723  that are configured to be placed in contact with and contour to the user&#39;s forehead and are held against the user&#39;s forehead through the strap  701 . The transducers  725  and  727  are coupled to the control unit  703  through sealed electrical connections  731  and  733  to receive processed content data generated from the control unit  703 , which converts the content data to bone conduction signals that are then transmitted to the user through the user&#39;s forehead to generate audible signals within one or more cavities of the user&#39;s head  702 .  
      In accordance with yet further embodiments of the invention, a system  800 , such as described with reference to  FIGS. 1 and 2 A- 2 C,  3 A- 3 B and  4 A- 4 B, and shown in  FIGS. 8A-8B , includes a control unit  811  with a timing circuit. The timing circuit is preferably programmable to allow a user to select a frequency of timing signals or a beat (a range of frequencies and/or sequence of timing signals with a range of frequencies) through one or more input buttons  805  and  805 ′. The control unit  811  can include all of the necessary components to receive, store and play content data files and/or receive and transmit radio communication signals. The control unit  811 , in addition to the timing circuit, can include, for example, a processor, a memory unit, a power source, an amplifier circuit, a radio transmitter, a radio receiver and an antenna, such as described in detail above. The system  800  can be used as a coaching device to provide audible cues at the selected frequency or beat to be followed during an exercise routine or other repetitive motion activity. The audible cues help the user to regulate the pace of the exercise routine or repetitive motion activity. For example, the system  800  can be used by swimmers, wherein the system  800  is configured to detachably coupled to swim goggles through an attachment feature or clip  807 .  
      Referring to  FIG. 8A , the system  800  includes a waterproof housing  801  for housing the control unit  811  and all of the necessary circuitry, such as described above. The system  800  can also include an input port  821  for downloading content data, programs or other data from a computer or other compatible device. Where the control unit  811  includes a radio receiver, the system  800  can be programmed or operated remotely using a master controller and/or communication signals can be sent to the system  800  through the master controller or any other device with a compatible radio transmitter. The system  800  can also include a display  803  for showing a graphic representation of the operational state of the system, such as the currently selected program, frequency or beat rate, the time of day, names of content data or files stored, programs that are available on the system  800  or any other information which may be useful to the user.  
      In use, a sealed diaphragm  815  of a built-in bone conduction speaker is held against and conforms to a portion of a user&#39;s head. The sealed diaphragm  815  can be held against the portion of the user&#39;s head with any suitable headgear, such as described above. The timing circuit generates timing signals at a selected frequency or beat. The timing signals are converted to vibrations through a transducer  813  with an oscillating diaphragm  817 . The vibrations from the oscillating diaphragm  817  are transferred to the sealed diaphragm  815  through any suitable mechanism and to the portion of the user&#39;s head. The vibrations move through bone in the user&#39;s head and generate audible representations of the timing signals within one or more cavities of the user&#39; head, such as the user&#39;s inner ears. Other features of systems that include timing circuits are described in U.S. patent application Ser. No. 10/632,464, filed Aug. 1, 2003, and titled “ELECTRONIC PACE REGULATING, TIMING, AND COACHING DEVICE AND SYSTEM,” the contents of which are hereby incorporated by reference.  
      There are a number of devices available for delivering content data to a user electronically in an audible form. However, many of these devices are not well suited for use while performing other activities where the user would like to or needs to hear other sounds in the environment. Further, many of the currently available devices are not well suited to operate in aquatic environments and/or are not configured to deliver music to a user and to operate as a two-way communication system.  
      The present invention has been described in terms of specific embodiments incorporating details to facilitate the understanding of the principles of construction and operation of the invention. As such, references, herein to specific embodiments and details thereof are not intended to limit the scope of the claims appended hereto. It will be apparent to those skilled in the art that modifications can be made in the embodiment chosen for illustration without departing from the scope of the invention.