Abstract:
A wireless listening system includes a base operable to receive an electrical signal corresponding to an audio signal, including the ring of an incoming telephone call, up-convert the audio signal to an infrared signal, and transmit the infrared audio signal wirelessly therefrom, and a wireless headset operable to selectably receive either the infrared audio signal transmitted by the base, or an infrared signal corresponding to an audio signal transmitted by a public address system, down-convert the received signal back into the audio signal, and audibly reproduce the audio signal to a wearer of the headset. The system enables a hearing impaired listeners to enjoy their favorite audio programs without disturbing nearby persons with normal hearing and without missing an incoming telephone call, and is also compatible with public IR PA systems currently used to assist the hearing impaired community.

Description:
BACKGROUND 
     This disclosure relates to wireless communication systems in general, and in particular, to wireless listening systems for the hard-of-hearing that use infrared signals to enable such users to hear and better understand the sound from home stereos, televisions, computers, public address systems, theaters and the like, while also providing the ability to alert the user to incoming telephone calls. 
     Nearly 34 million Americans are affected by a hearing impairment that is sufficiently profound as to prevent them from enjoying television, music and other audio program broadcasts. In addition to private settings in which the hard-of-hearing may not be able to hear sound broadcasts adequately, this segment of the population may also be excluded from hearing in public meetings, church services or theater events and the like. 
     There are currently a number of personal sound amplification devices on the market that amplify sounds from stereos, televisions and computers through the standard 2.3 MHz and 2.8 MHz infrared (IR) communication protocols. However, these devices are not compatible with the standard 95 KHz public broadcast protocol. Moreover, the devices that are compatible with the 95 KHz public broadcast standard are not compatible with the 2.3 MHz and 2.8 MHz systems. Moreover, there are currently no IR listening devices on the market that are capable of being connected to a telephone line and that can give notification to a user of incoming telephone calls while they are listening to an audio program with the devices. 
     Accordingly, there is a need on the part of hard-of-hearing users for a wireless listening system that enables the user not only to hear and better understand sounds broadcast by both private and public sources, but that also notifies the user of incoming telephone calls while listening to an audio program. 
     BRIEF SUMMARY 
     In accordance with the exemplary embodiments thereof described herein, a wireless listening system is disclosed that enables a hard-of-hearing user to experience amplified, enhanced sound reproduction from televisions, stereos, computers and other electrical appliances using the standard 2.3 and 2.8 MHz IR communication protocols, and also to use the wireless headset of the system in public settings, such as, e.g., city council meetings, school auditoriums, movie theaters and churches, using an integral 95 KHz infrared communication protocol, and further, to be notified of incoming telephone calls while using the system. 
     In one exemplary embodiment, the system comprises a base that is operable to receive an electrical signal corresponding to an audio signal, including a ring signal corresponding to an incoming telephone call, up-convert the audio signal to an infrared signal, and transmit the infrared audio, signal wirelessly therefrom, and a wireless headset that is operable to selectably receive either the infrared audio signal transmitted by the base, or alternatively, an infrared signal corresponding to an audio signal transmitted by a public address system, down-convert the received signal back into the audio signal, and audibly reproduce the audio signal to a wearer of the headset, including the production of an audible notification of the incoming telephone call. 
     In another exemplary embodiment, the base frequency modulates a carrier signal with the audio and incoming telephone call signals, and the audio signal may comprise a stereo signal, i.e., separate left and right sound channels, and the base and the headset are respectively operative to receive, up-convert and transmit, and to receive, down-convert, and audibly reproduce each of the channels to the wearer simultaneously and separately from each other. The left and right channels of the audio program may be respectively transmitted by the base and received by the headset on different carrier frequencies, which in one particular exemplary embodiment may comprise carrier frequencies of 2.3 MHz and 2.8 MHz, respectively. The headset of the system is also capable of receiving an infrared audio signal transmitted by the public address source on a carrier frequency of 95 KHz. 
     A better understanding of the above and many other features and advantages of the novel wireless listening system of the present invention may be obtained from a consideration of the detailed description of some exemplary embodiments thereof below, particularly if such consideration is made in conjunction with the appended drawings, wherein like reference numerals are used to identify like elements illustrated in one or more of the figures thereof. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an upper, right side and front perspective view of an exemplary embodiment of a wireless listening system in accordance with the present invention, showing a wireless headset unit of the system docked in an associated base unit thereof; 
         FIG. 2  is an upper right side and front perspective view of the base unit of the exemplary system; 
         FIG. 3  is an upper rear perspective view of the wireless headset unit of the system; 
         FIG. 4  is a functional block diagram of the base unit of the system; 
         FIG. 5  is a functional block diagram of the headset unit of the system; 
         FIG. 6  is a rear elevation view of the base of the system showing various signal connection inputs to the base; 
         FIG. 7  is a top, front perspective view of the base and headset units showing the adjustment of various controls thereof; and, 
         FIG. 8  is a perspective view of the base and headset units of the listening system shown separated from each other by a distance, illustrating the base unit and a public broadcasting transmitter wirelessly transmitting respective IR signals to the headset unit of the system. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  is an upper, right side and front perspective view of an exemplary embodiment of a wireless listening system  10  in accordance with the present invention, showing a wireless headset unit  12  of the system docked in an associated base unit  14  thereof. The listening system  10  is intended for the hard-of-hearing, and accordingly, the amplified headset  12  and a base  14  are specifically designed for transmission and reception of infrared signals for the purpose of reproducing sound generated from home stereos, televisions, computers, and the like, as well as public address systems, such as theaters, auditoriums and other public sound sources, while also providing the ability to alert the user to an incoming telephone call. The system is thus designed as a consumer electronic solution for those who experience a mild-to-severe hearing loss who wish to experience both public and private sound broadcasts. 
     The base unit  14  of the exemplary system  10  is illustrated in the upper right and front side perspective view of  FIG. 2 , and comprises a low-profile housing  16  adapted to sit atop a TV, radio, stereo set, book shelf or the like, and to radiate IR signals forwardly, across a substantially wide angle of transmission, and towards a hard-of-hearing listener wearing the headset  12  of the system, as described in more detail below. The base includes a receptacle  18  adapted to receive the headset in a complementary, plug-in engagement, as illustrated in  FIG. 1 , and as discussed below, a battery charger that is operative to charge a rechargeable battery contained in the headset while the base and the headset are engaged with each other. The base additionally includes a pair of separate spare battery charging receptacles  20 A and  20 B, each adapted to receive and continuously charge a spare battery (not illustrated) for the headset. This arrangement ensures that the headset of the system will always have an ample source of power available, even with extended use away from home and remote from the base. 
       FIG. 4  is a functional block diagram of the base unit  14  of the system  10 , and  FIG. 6  is a schematic rear elevation view of the base showing the various signal connection inputs thereto. As illustrated in the particular exemplary embodiment of  FIGS. 4 and 6 , the signal inputs include a DC power input  22  from, e.g., a transformer  24  that plugs into a conventional AC wall power receptacle  26 , Left and Right audio channel electrical signal inputs  28 L and  28 R (e.g., RCA jacks), that are output by an electrical appliance  30 , such as a television, stereo or computer, and a telephone “Line” input  32 , e.g., a Public Switched Telephone Network (PSTN) Line input, fed from, e.g., a conventional RJ11 telephone wall jack  34 . The base also includes an RJ11 jack  36  that enables a standard telephone set  38  to be coupled to the Line input through the base. 
     As illustrated in  FIG. 6 , the base  14  also includes a socket  40  for coupling a microphone (not illustrated) into the base, which is provided to make the system  10  “backwards-compatible” to older electrical appliances  30 , such as a TV, that lack audio output jacks that enable coupling of its audio program electrical signals directly to the base. By connecting the microphone to the base and then disposing the microphone adjacent to the loudspeaker of the appliance, the microphone serves to transform the audio signal from the speaker into a corresponding electrical signal that is transmitted to the headset  12  in the same manner that the Left and Right channel and incoming telephone call notification signals are transmitted thereto, as described below. 
     The exemplary system  10  may also include an adapter cable  42  that enables a monophonic audio source (not illustrated) to be coupled to the Left and Right channel inputs  28 L and  28 R of the base  14 , as well as a “Stereo/Mono” selector switch  44  that enables the operation of the base to be switched between a monophonic mode, in which the audio program signal input to the Left channel input  18 L is transmitted by the base on both transmit channels, and a stereophonic mode, in which each of the Left and Right channels of the audio program are transmitted on a separate channel, as described in more detail below. 
     As illustrated in the functional block diagram of  FIG. 4 , the base  14  comprises three main functional sections of components, viz., an incoming telephone call notification signal generator  46 , an audio signal mixing, up-converting and transmitting section  48 , and a headset battery charging section  50 . The incoming telephone call notification signal generator comprises a bridge  52  for rectifying the incoming telephone “ring” signal from the telephone Line input  32 , a detection circuit  54  for detecting the ring signal, and a ring generator  56  that generates a telephone ringing signal in response to an incoming telephone call and outputs it to the audio signal mixing, up-converting and transmitting section  48  of the base. 
     The audio mixing, up-converting and transmitting section  48  of the base  14  comprises a signal mixer  58 , a signal up-converter  60 , a transmission amplifier  62 , and a transmitter  64  for radiating the transmitted signals from the base. The audio section is operable to receive the respective electrical signals corresponding to the Left and Right audio channels signals, the incoming telephone call notification signal, and selectably, the microphone input signal, and to then up-convert the respective audio signals to infrared signals and transmit the infrared audio signals wirelessly from the base  14  to the wireless headset  12 , as illustrated in  FIG. 8 . 
     In the particular exemplary embodiment described and illustrated, the audio section  48  of the base  14  frequency modulates two separate infrared carrier signals at 2.3 MHz and 2.8 MHz, respectively, with the audio and incoming telephone call signals, and outputs them both simultaneously from the base  14  via the amplifier  62  and transmitter  64 . Thus, each of the Left and Right channels of a stereo audio program is carried on a separate channel, each having a frequency response of 20 Hz-20 KHz, for maximum channel separation and sound fidelity. However, as those of skill in the art will appreciate, other modulation and/or multiplexing techniques can also be used. The transmitter  64  comprises a plurality of light emitting diodes (LEDs) operating at a wavelength of, e.g., 850 nm, which are arrayed behind a IR-transparent front panel  17  (see  FIG. 1 ) of the base, to radiate the up-converted audio signals forwardly, across a wide angle of transmission, over a line-of-sight range of up to 30 ft., and to the headset  12  of the system. 
     As a power-saving feature, the base  14  also includes a timer circuit that deactivates the base, except for the headset battery charging section  50  thereof described below, after a predetermined period of time during which no audio signal is input to the base, and that automatically reactivates the base when such an audio signal is input thereto. 
     As discussed above, the battery charging section  50  of the base  14  comprises circuitry adapted to automatically recharge the battery of the headset  12  while the headset is plugged into the complementary receptacle  18  of the base, as illustrated in  FIG. 1 , as well as to continuously charge a pair of spare headset batteries (not illustrated) respectively received in the spare battery charging receptacles  20 A and  20 B of the base. This arrangement enables the user to take two fully charged backup batteries, as well as the one contained in the headset, for extended periods of use remote from the base. 
       FIG. 3  is an upper rear perspective view of the wireless headset unit  12  of the listening system  10 , and  FIG. 5  is a functional block diagram thereof. As illustrated in  FIG. 3 , the headset comprises a main body  70  and a pair of stethoscope-like earpieces  72 L and  72 R, each of which is equipped with a respective ear bud  74 L and  74 R adapted to be inserted into a respective one of the wearer&#39;s left and right ears. In use, the main body of the headset hangs down, pendant-like, from the ear pieces and below the wearer&#39;s chin. As a power-conserving feature, the two earpieces are biased toward each other, e.g., with a spring mechanism, and are operative to automatically activate the headset when spread apart from each other, i.e., while the headset is being worn, and to automatically deactivate the headset when biased together, e.g., when the wearer takes the headset off and inserts it into the charging receptacle  18  of the base  14 , as illustrated in  FIG. 7 . 
     As illustrated in  FIG. 5 , the headset  12  comprises three main functional sections, a power supply section  76 , a receiver and down-converter section  78 , and a signal transforming and amplification section  80 . As discussed above, the power supply section comprises a rechargeable battery  82 . In one preferred exemplary embodiment, the battery comprises a nickel metal hydride (NiMH) battery having a minimum (per charge) battery life of about 6 hours. 
     The receiver and down-converter section  78  of the headset  12  comprises an infrared light detector  84  for detecting infrared light signals transmitted from both the base unit  14  and other public address transmitters, as described below, and a signal down-converter section  86 . The detector outputs the infrared signals received to the down-converter, which functions to demodulate the audio signals from the infrared signals into two, separate, left and right audio-frequency signals  88 L and  88 R that are then input to the transforming and amplification section  80 . The transforming and amplification section comprises a pair of adjustable-gain amplifiers  90 L and  90 R and an associated pair of electro-acoustic transducers, or earphones  92 L and  92 R that respectively amplify and transform the left and right audio channel electrical signals  88 L and  88 R into acoustic sound signals that are respectively input into the left and right ears of the listener via the respective earpieces  72 L,  72 R and ear buds  74 L,  74 R of the headset. The amplifiers are capable of adjustably applying a minimum of 50 dB and 120 dB SPL of amplification to the audio signal reproduced to the ears of the listener. 
     In addition to its capability of receiving and down-converting the infrared signals respectively transmitted by the base  14  on the two 2.3 and 2.8 MHz carrier frequencies, as discussed above, the receiver and down-converter section  78  of the headset  12  is also capable of receiving and down-converting infrared signals broadcast by a source  94  via the standard 95 KHz public address protocol used by many theaters, churches, and sponsors of pubic events, as illustrated schematically in  FIG. 8 . Thus, the wireless headset is not limited to use only in conjunction with the base unit  14 , but also enables the hard-of-hearing user to better hear and understand audio programs in other environments that are equipped with a standard 95 MHz infrared sound transmission system. 
       FIG. 7  is a perspective view illustrating the headset  12  being plugged into the battery charging receptacle  18  of the base  14 , and shows the adjustment of the various control features thereof. As illustrated in the left inset figure, the headset includes the following controls, located on the upper edge of the headset: An on/off switch  96  for manually activating/deactivating the headset, a “home/away” switch  98  that enables the user to select between use of the headset at home and in conjunction with the base, or alternatively, away from home and in conjunction with a public address broadcasting source  94 , as discussed above, and a volume control switch  100 . As illustrated in the right inset figure, the side surface of the headset also includes Left and Right channel gain controls  102 L and  102 R and a control  104  for adjusting the balance between the left and right channels, all of which, in the particular exemplary embodiment illustrated, are adjustable with a small screwdriver. Of course, other control placement and means of adjustment are also possible. 
     In accordance with the exemplary embodiments described herein, the novel listening system  10  of the present invention comprises an amplified, stereo, infrared (IR) listening system with telephone ring notification. It enables hard-of-hearing people with moderate to severe hearing loss to better hear and understand, e.g., television programs, without having to turn up the TV&#39;s sound volume and without disturbing the normal-hearing individuals in the household. The user can control the volume and tone of the program directly from the headset without affecting the TV settings. The listening system thus reduces background noise and overcomes distance by delivering audio directly from the sound source to the listener&#39;s ears. 
     Unlike conventional headsets, which only increase sound volume, the system  10  of the present invention improves the clarity of sound of, e.g., a TV program. This is crucial for many hard-of-hearing people who can hear sounds but have difficulty understanding certain sound frequencies. The system enhances a hard-of-hearing person&#39;s hearing experience not only while listening to television, but also while listening to stereo, movies or in other public environments that are equipped with a standard 95 MHz infrared sound transmission system. 
     The system  10  also provides incoming telephone call ring notification to the user while the user is listening to an audio program at home. When the telephone  38  rings, the base unit  14  transmits a corresponding IR “ringing” signal to the headset  12 . In response, the headset emits a “beep” or other audible indicator to notify the wearer of the incoming call. This notification feature ensures that users will not miss a telephone call while they are listening to their favorite TV or other types of programs. 
     The system  10  is compatible with satellite, cable, digital, plasma and high definition (HD) television systems. The dual-channel 2.3 and 2.8 MHz carrier frequencies provide professional level stereo sound with minimum interference and cross-talk. The 95 kHz frequency capability enables the headset of the system to be compatible with the majority of public IR public address (PA) systems widely available to assist the hearing impaired community. 
     By now, those of skill in this art will appreciate that many modifications, substitutions and variations can be made in and to the novel wireless listening system of the present invention without departing from its spirit and scope. In light of this, the scope of the present invention should not be limited to that of the particular embodiments illustrated and described herein, as they are only exemplary in nature, but instead, should be fully commensurate with that of the claims appended hereafter and their functional equivalents.