Abstract:
A method for providing telephone services for the hearing-impaired includes establishing a conference call between a hearing-impaired party, a hearing party and a communication assistant. The hearing party sends a voice message to the communication assistant. The communication assistant converts the voice message into a corresponding text message and transmits the text message to the hearing-impaired party. The text message is displayed to the hearing-impaired party using a device that includes a modem. The modem outputs a synchronization tone in response to receiving the text message. The synchronization tone and other tones may then be filtered to ensure that they do not reach the communication assistant and the hearing party.

Description:
FIELD OF THE INVENTION 
     The present invention relates to filtering signals and, more particularly, to filtering signals in a conference call environment. 
     BACKGROUND OF THE INVENTION 
     A conventional telecommunication device for the deaf/teletype (TDD/TTY) enables people who are hard of hearing or deaf to communicate with other parties via standard telephone lines. For example, one way in which a deaf party may communicate with another party is if both parties use a TDD. In this case, a calling party may type using a standard keyboard included with the TDD and the called party reads the message on a display associated with his/her TDD. The called party may similarly type a message using his/her TDD and the calling party may read the message using his/her display. 
     A second way in which a hearing-impaired/deaf person may communicate via standard telephone lines is referred to as voice carry over (VCO). In this case, a conference call is established between a first party, a communication assistant (CA) (also referred to as a conference administrator) and a second party. The first party may be a deaf person who has a TDD/TTY and the second party may be a person with normal hearing who does not have a TDD/TTY device. 
     When the deaf party wishes to make a call, he/she dials a telephone number for the CA and tells the CA the telephone number to which he/she would like to be connected. The CA may dial the number and provide a greeting to the hearing party. When the hearing party speaks, the CA types what is slid and the deaf party reads the text using the TDD/TTY&#39;s display. The deaf party may respond to the message on the display by speaking to the hearing party, whereby the deaf party&#39;s voice is transmitted to the hearing party in a normal manner. In this manner, the deaf party may communicate with hearing and hearing-impaired parties using conventional telephone lines and conventional TDD/TTY equipment. 
     In the second scenario described above (i.e., VCO mode), a conference bridge is established to enable the three parties (the hearing-impaired party, the CA and the hearing party) to communicate. The hearing-impaired party&#39;s TDD/TTY includes a conventional modem for receiving the text messages from the CA. When the CA begins to type and the text data is transmitted to the TDD/TTY, the TDD/TTY modem responds with a synchronization (sync) tone. In typical systems, this sync tone is transmitted at a very high decibel level and is received at the conference bridge. As a result, both the CA and the hearing party receive the high decibel sync tone. This sync tone is extremely bothersome and even painful for the CA and the hearing party. Other annoying tones may also be transmitted from TDD/TTY echo path to the CA and the hearing party. 
     To combat the annoying sync tone and other tones from being transmitted to the CA and the hearing party, some systems terminate the receive leg of the connection from the conference bridge to the TDD/TTY each time the CA types. That is, the system breaks the receive connection between the conference bridge and the TDD/TTY to prevent signals from the TDD/TTY modem from reaching the conference bridge. In this case, the connection between the CA and the TDD/TTY modem remains in place so that the TDD/TTY can receive the text message from the CA. There are, however, several drawbacks with this approach. 
     For example, one drawback with this approach is that the automatic gain control (AGC) of the conference bridge goes into spasm when the connection is frequently broken and then re-established. That is, the conference bridge may first over-amplify and then over-attenuate the receive leg of the connection from the conference bridge to the hearing-impaired party when the connection is re-established. In addition, a loud pop often occurs on the conference bridge caused by the re-synchronization of the pulse coded modulated (PCM) data streams between the CA&#39;s modem and the TDD/TTY&#39;s modem. 
     Another drawback with terminating and re-connecting the connection from the TDD/TTY to the conference bridge is that the first word or words spoken by the hearing-impaired party when he/she responds to the CA?s text message is often clipped. That is, the hearing-impaired party&#39;s first word(s) are often not transmitted to the hearing party because the connection to the conference bridge is not re-established before the non-hearing party begins to speak. 
     SUMMARY OF THE INVENTION 
     There exists a need for a method and apparatus that improve problems associated with a conference call involving a TDD/TTY. 
     These and other needs are met by the present invention, where signals from a TDD/TTY device are filtered during a conference call. By selectively filtering transmissions from the TTD/TTY, the annoying/painful tones associated with a TDD modem are not transmitted to the CA and the hearing party. 
     According to one aspect of the invention, a method for providing telephone services for the hearing-impaired is provided. The method includes establishing a conference call between a hearing-impaired party, a hearing party and a communication assistant. The method also includes sending a voice message from the hearing party to the communication assistant, generating a text message by the communication assistant, the text message corresponding to the voice message and transmitting the text message. The method further includes receiving the text message by the hearing-impaired party using a device that includes a modem, the modem outputting a synchronization tone in response to receiving the text message. The method also includes filtering the synchronization tone so that the synchronization tone does not reach the communication assistant and the hearing party. 
     Another aspect of the present invention provides a computer-readable medium that includes stored sequences of instructions that are executed by a processor. The instructions cause the processor to allocate resources for maintaining a conference call between a hearing-impaired party, a hearing party and a communication assistant and pass a voice message generated by the hearing party to the communication assistant. The instructions also cause the processor to forward a text message generated by the communication assistant to the hearing-impaired party and receive a synchronization tone from a modem associated with the hearing-impaired party. The instructions further cause the processor to filter the synchronization tone so that the synchronization tone does not reach the communication assistant and the hearing party. 
     According to a further aspect of the invention, a device for facilitating communications with a hearing-impaired party is provided. The device includes a modem, a processing device coupled to the modem and a display. The modem is configured to receive data and the processing device processes the received data and outputs text data. The display receives the text data from the processing device and displays a message to the hearing-impaired party. The processing device is also configured to block data transmissions from the modem. having at least one predetermined frequency from being transmitted to another party. 
     Other features and advantages of the present invention will become readily apparent to those skilled in this art from the following detailed description. The embodiments shown and described provide illustration of the best mode contemplated for carrying out the invention. The invention is capable of modifications in various obvious respects, all without departing from the invention. Accordingly, the drawings are to be regarded as illustrative in nature, and not as restrictive. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Reference is made to the attached drawings, wherein elements having the same reference number designation represent like elements throughout. 
     FIG. 1 is an exemplary system in which methods and systems consistent with the present invention may be implemented. 
     FIG. 2 is a block diagram of an exemplary host, device in which systems and methods consistent with the present invention may be implemented. 
     FIG. 3 is an exemplary flow diagram, consistent with the present invention, illustrating processing associated with a conference call. 
     FIG. 4 is an exemplary diagram of the filter of FIG. 1 consistent with an implementation of the present invention. 
    
    
     DETAILED DESCRIPTION 
     Systems and methods consistent with the present invention avoid the problems associated with conventional conference calls involving TDD/TTYs by filtering signals transmitted from the TDD/TTY modem. By filtering signals transmitted from the TDD/TTY modem, annoying tones are blocked without breaking the connection from the TDD/TTY to a conference bridge. 
     SYSTEM OVERVIEW 
     FIG. 1 is a block diagram of an exemplary system  100  in which methods and systems consistent with the present invention may be implemented. The system  100  includes a bridge  110 , conference resources  120 ,  130  and  140 , bus  150 , TDD  160 , CA  170 , telephone  180  and filter  190 . The exemplary configuration illustrated in FIG. 1 is for simplicity. It should be understood that other devices may be included in system  100  in implementations consistent with the present invention. 
     The bridge  110  may include a conventional conference bridge device that links multiple parties in a conference call. Conference resources  120 ,  130  and  140  represent conventional resources, such as the telephone circuits, switching devices, software or hardware controlled devices, etc., involved in completing the conference call for each of the respective participants. In the exemplary system  100 , conference resource  120  is associated with a hearing-impaired party communicating via TDD  160 , conference resource  130  is associated with CA  170  and conference resource  140  is associated with a hearing party communicating via telephone  180 . 
     The bus  150  may be a time division multiplexed (TDM) bus that provides each of the parties involved in the conference call with a full-duplex connection to the respective conference resources  120 - 140 . Alternatively, the connection between the bus  150  and one or more of the conference resources, such conference resource  120  may be half-duplex. In an exemplary implementation, bus  150  may represent a multi-vendor integration protocol (MVIP) bus, a signal computing system architecture (SCSA) bus or another type of bus. In each case, conference resources  120 - 140 , TDD  160 , CA  170  and telephone  180  may transmit/receive data to/from each other via bus  150 . 
     The TDD  160  may be a conventional TDD/TTY device that includes a modem  162 , a display  164 , a keyboard  166  and a microphone  168 . It should be understood that TDD  160  may include a bus (not shown) that interconnects some or all of the components of the TDD  160 . It should also be understood that TDD  160  may include additional components, such as a processor or microprocessor (not shown) that processes information and controls the components of TDD  160 . In an exemplary implementation, the TDD  160  may include an acoustic coupler that receives a conventional telephone handset. In this implementation, the microphone  168  may be the microphone portion of the telephone handset. When the user wishes to talk, he/she may pick up the telephone from the acoustic coupler and speak. When the user wishes to receive data from the CA  170 , the user may place the telephone in the acoustic coupler, thereby activating the modem  162 . In other implementations, the TDD  160  may be a conventional TTY with a display screen and a separate telephone handset. 
     The CA  170  may represent any conventional CA workstation and operator used in a VCO environment. In most jurisdictions, when a deaf party wishes to make a call to a hearing party without a TDD or when someone without a TDD wishes to call a deaf party, he/she uses a telephone number designated for CAs. The CA  170  may include a modem  172 , a headset  174  and a keyboard  176 . It should be understood that CA  170  may include a processor or microprocessor (not shown) that performs processing associated with transmitting data and a bus (not shown) that interconnects some or all of the components of the CA  170 . It should also be understood that the CA  170  may include additional components, such as a display device (not shown) that displays information for the CA operator, such as information that he/she types via keyboard  176 . 
     The telephone  180  represents a conventional telephone used by a hearing party to communicate with the CA  170  and the hearing-impaired party via bridge  110 . The telephone may be a standard telephone, a cordless telephone, a cellular telephone or any other type of conventional telephone. 
     In an exemplary implementation consistent with the present invention, the CA  170  may receive a call from a hearing-impaired party. The CA may receive the telephone number of the party that the hearing-impaired party wishes to call and may complete a conference call to telephone  180  via bridge  10  in a conventional manner. The CA  170  may then listen for voice messages from the hearing party and types the corresponding messages via keyboard  176 . The text message is transmitted from CA  170  via modem  172 . The TDD modem  162  receives the text message and displays the text via display  164 . 
     The filter  190  may represent a voice frequency (VF) filter that is designed to pass normal VF signals and filter out signals having one or more specific frequencies. According to an exemplary implementation consistent with the present invention, the filter  190  receives data streams from the TDD  160  and performs a filtering process on the received data streams. In an exemplary implementation, the TDD  160  transmits data streams onto bus  150  and filter  190  receives these data streams via the bus  150 . The filter  190  may then perform its filtering process, as described in more detail below. 
     According to an exemplary implementation consistent with the present invention, all or some of the components of the bridge  110 , conference resources  120 - 140  and filter  190  may be implemented in a host device or controlled by a host device, indicated by the dotted lines and labeled  200  in FIG.  1 . The host device  200  may provide the platform for establishing and maintaining the conference call between the hearing-impaired party, the CA operator and the hearing party, in addition to filtering signals from the TDD  160 , as described in more detail below. 
     FIG. 2 illustrates an exemplary host device  206  in which systems and methods consistent with the present invention may be implemented. The host device  200  includes a bus  210 , a processor  220 , a memory  230 , a read only memory (ROM)  240 , a storage device  250 , an input device  260 , an output device  270 , and a communication interface  280 . The bus  210  permits communication among the components of the host device  200 . 
     The processor  220  may include any type of conventional processor or microprocessor that interprets and executes instructions. The memory  230  may include a random access memory (RAM) or another dynamic storage device that stores information and instructions for execution by the processor  220 . Memory  230  may also be used to store temporary variables or other intermediate information during execution of instructions by processor  220 . 
     ROM  240  may include a conventional ROM device and/or another static storage device that stores static information and instructions for processor  220 . The storage device  250  may include a magnetic disk or optical disk and its corresponding drive and/or some other type of magnetic or optical recording medium and its corresponding drive for storing information and instructions. 
     The input device  260  may include any conventional mechanism that permits an operator to input information to the host device  200 , such as a keyboard, a mouse, a pen, voice recognition and/or biometric mechanisms, etc. The output device  270  may include any conventional mechanism that outputs information to the operator, including a display, a printer, one or more speakers, etc. The communication interface  280  may include any transceiver-like mechanism that enables the host device  200  to communicate with other devices and/or systems. For example, the communication interface  280  may include a modem or an Ethernet interface to a LAN. Alternatively, communication interface  280  may include other mechanisms for communicating via a network. 
     The host device  200 , consistent with the present invention, provides a platform through which a conference call may be established between TDD  160 , CA  170  and telephone  180 . According to an exemplary implementation, the host device  200  performs processing associated with establishing and maintaining the conference call in response to processor  220  executing sequences of instructions contained in memory  230 . Such instructions may be read into memory  230  from another computer-readable medium, such as a data storage device  250 , or from a separate device via communication interface  280 . It should be understood that a computer-readable medium may include one or more memory devices or carrier waves. Execution of the sequences of instructions contained in memory  230  causes processor  220  to perform the acts that will be described hereafter. In alternative embodiments, hard-wired circuitry may be used in place of or in combination with software instructions to implement the.present invention. Thus, the present invention is not limited to any specific combination of hardware circuitry and software. 
     EXEMPLARY PROCESSING 
     FIG. 3 is an exemplary flow diagram, consistent with the present invention, illustrating processing associated with communications between a non-hearing party using TDD  160 , a CA  170  and a hearing party using telephone  180 . Assume that the hearing-impaired party wishes to make a telephone call. In this example, processing begins when the hearing-impaired party makes a telephone call to CA  170  (act  310 ). After the call to the CA  170  is completed, the hearing-impaired party may verbally provide the telephone number that he/she wishes to call (act  310 ). The CA  170  may then dial the number-of the desired party. In the example illustrated in FIG. 1, assume that the CA  170  dials the telephone number associated with telephone  180 . 
     The responsible service provider (e.g., the local telephone company, a long distance telephone provider, etc.) establishes a conference call between the three parties via bridge  110  (act  320 ). In an exemplary implementation, the host device  200  allocates and controls conference resources  120 - 140  and bridge  110  to establish and maintain the conference call. After the connection to the hearing party is established, the CA  170  may provide a voice greeting to the hearing party informing the hearing party that a telephone call from a hearing-impaired person is to commence (act  320 ). The CA  170  may also provide the name and other information relating to the hearing-impaired party. 
     The hearing party may respond with a verbal greeting intended for the hearing-impaired party (act  330 ). The CA  170  receives the audio message via headset  174  and types the corresponding message using keyboard  176  (act  340 ). After typing the message, or while the CA  170  is typing the message, the CA modem  172  receives and begins transmitting the text message to bus  150  for transmission to TDD  160  (act  350 ). In an exemplary implementation, the text message from the CA modem  172  may be transmitted via bus  150  to conference resource  130  and on to bridge  110 . Bridge  110  may then route the text message to TDD  160  via conference resource  120  and bus  150 . It should be understood that in alternative implementations, the message from the CA modem  172  to TDD  160  may be routed in other ways. 
     The TDD modem  162  receives the text message and after processing by the TDD  160 , the text message is displayed for the hearing-impaired user on display  164  (act  360 ). The TDD modem  162 , consistent with the present invention, may also output a synchronization tone when it begins receiving data from CA  170  (act  360 ). The sync tone is normally used to synchronize data transmission/reception between two modems. According to an exemplary implementation, the sync tone may have a frequency of about 1150 Hz. 
     The TDD modem  162  transmits the sync tone via bus  150  to filter  190 . In an exemplary implementation, the filter  190  receives the sync tone, determines that the sync tone has a frequency of 1150 Hz and blocks the 1150 Hz sync tone from being passed to the conference resource  120  and bridge  110  (act  370 ). This prevents the sync tone from being transmitted to the CA  170  and telephone  180 . According to an exemplary implementation, the filter  190  may be designed to block signals having a frequency of 1150 Hz plus or minus some value. That is, the filter  190  may be designed to take into consideration variances in equipment, tolerances, etc. For example, the filter  190  may block&#39;signals having a frequency of 1150 Hz±10 Hz. In this case, the filter  190  determines the frequency of signals it receives and when the signal is between 1140 and 1160 Hz, the filter  190  blocks the signal from being transmitted to conference resource  120  and ultimately, from being transmitted to other parties via bridge  110 . 
     Filter  190 , consistent with the present invention, may also block signals having other frequencies (act  380 ). For example, TDD modem  162  may transmit data via a frequency shift keying (FSK) scheme at frequencies of 1400 Hz and 1800 Hz, respectively. That is, the FSK scheme may transmit a series of “1s” and “0s” at frequencies of 1400 Hz and 1800 Hz, respectively. 
     In a normal VCO environment, the hearing-impaired deaf party is supposed to respond to text displayed on his/her display  164  by providing normal audio responses. That is, the hearing-impaired party is not supposed to respond by using the keyboard  166 . If for some reason, however, the hearing-impaired party-begins typing via keyboard  166 , the TDD modem  162  will transmit the data and the CA  170  and hearing party will hear high decibel tones associated with these data transmissions. Therefore, in order to avoid these tones from reaching the CA  170  and the hearing party, the filter  190  may also determine if signals having a frequency of either 1400 or 1800 Hz plus or minus some value (e.g., 10 Hz) are being transmitted from TDD  160 . If the filter  190  determines that signals having these frequencies (i.e., 1400 or 1800 Hz) are being transmitted from TDD  160 , filter  190  may block these transmissions as well. 
     In this manner, if TDD modem  162  begins transmitting either sync tones or transmissions associated with data entered via keyboard  166  after the conference call is established, the filter  190  will block these signals from reaching the bridge  110 . 
     When the hearing-impaired party wishes to respond to the text message displayed on display  164  in the intended manner in a VCO environment, he/she may provide a normal audio response via microphone  168  (act  390 ). The microphone  168 , consistent with the present invention, may be the microphone portion of a conventional telephone handset. As discussed previously, according to one implementation, the TDD  160  many include a conventional telephone handset that sits in an acoustic coupler when the hearing-impaired user wishes to receive text messages. When the hearing-impaired user wishes to answer the message, he/she picks up the telephone handset from the acoustic coupler and verbally responds. This audio message may be transmitted to the hearing party and the CA  170  via bridge  110  (act  390 ). Since the filter  190  is only designed to block frequencies of about 1150 Hz and to optionally block frequencies of about 1400 Hz and 1800 Hz, the large majority of the normal voice frequencies will pass through to bridge  110  to the hearing party and the CA  170 . 
     The process may then return to act  330  and each time the hearing party responds, the CA types a text message and transmits the text message to the TDD  160 . The filter  190  also remains active to ensure that sync tones and other tones from the TDD modem  162  are not transmitted to the other parties via bridge  110 . 
     Referring back to FIG. 1, the filter  190  is shown as a separate component. Filter  190 , as described in relation to FIG.  2  and according to an exemplary implementation of the present invention, may be implemented in software. In this implementation, the processor  220  performs an algorithm that determines the frequency of incoming signals and blocks the signals having the designated frequencies from passing to the bridge  110 . One of ordinary skill in the art would be able to develop such an algorithm using conventional digital signal processing techniques based on the description given herein. It should be understood, however, that filter  190  may also be implemented in hardware. 
     For example, FIG. 4 illustrates an exemplary filter  190 , consistent with a hardware implementation of the present invention. The filter  190  includes filter components  410 ,  420  and  430  coupled in series. Filter components  410 - 430  each include circuitry designed to “notch out” (i.e., block) signals of a particular frequency or range of frequencies. 
     In an exemplary implementation consistent with the present invention, filter component  410  filters out signals that have a frequency of about 1150 Hz. That is, the filter component  410  blocks signals having a frequency of about 1150 Hz±10 Hz from reaching conference resource  120  and ultimately, from being routed to the CA  170  and telephone  180  via bridge  110 . 
     In addition, as described previously, TDD modem  162  may transmit data using a FSK scheme in which a series of “1s” and “0s” may be transmitted at frequencies of 1400 Hz and 1800 Hz. In this implementation, filter component  420  may block signals having a frequency of about 1400 Hz (e.g., 1400±10 Hz) and filter component  430  may block signals having a frequency of about 1800 Hz (e.g., 1800±10 Hz). 
     In this manner, filter  190  blocks signals having specific frequencies, while letting other voice frequencies pass through the filter  190 . In this manner, filter  190  may selectively filter out annoying sync tones, other tones transmitted from the TDD  160  and echo tones, thereby ensuring that the CA  170  and the hearing party do not receive high decibel tones from TDD  160 . 
     In the hardware implementation illustrated in FIG. 4, the filter  190  may be located at the location of the entity responsible for establishing the conference call. Alternatively, the filter  190  may be located at the TDD  160 . In this case, a user&#39;s conventional TDD  160  may be retrofitted to include the filter  190 . Alternatively, the filter  190  may be inserted in the TDD  160  at the time of manufacturing. A switch could also be installed in the TDD  160  or retrofitted to the TDD  160  so that the user can bypass the filter  190  when the TDD is being used in a non-VCO, environment (i.e., the user is communicating with another hearing-impaired user with a TDD). The switch could also be used when the TDD  160  is first starting up and synchronization with the CA modem  172  may be necessary. 
     In any event, the details of the circuitry in filter components  410 ,  420  and  430  are not illustrated in FIG.  4 . One of ordinary skill in this art, however, would know how to design the particular circuitry based on the particular frequencies that the respective filter components  410 - 430  are designed to block. For example, conventional resistor, inductor, capacitor (RLC) circuits may be used to filter out the desired frequency(ies). Thus, the present invention is not limited to any specific combination of hardware circuitry. 
     In the manner described above, a TDD/TTY, user may use his/her TDD/TTY in a VCO mode while ensuring that annoying tones from the TDD/TTY modem are not transmitted via the conference call. 
     Systems and methods consistent with the present invention facilitate communications between hearing-impaired parties and hearing parties. An advantage of the invention is that hearing users are not forced to endure frequent and annoying tones associated with a TDD modem. Another advantage is that the present invention allows full time VCO routing of the receive connection from a conference bridge to a TDD/TTY. That is, the present invention does not break any connections to the conference bridge, thereby ensuring that none of the voice message from the hearing-impaired party is clipped while a connection is re-established. This results in more reliable and accurate conversations between hearing-impaired parties, the CA and hearing parties and increases satisfaction with the VCO service. Avoiding frequent re-synchronizing will also increase VCO throughput since the time spent re-synchronizing the TDD/TTY device is reduced. In addition, reducing the number of times that the TDD/TTY modem is re-synchronized enables the line levels to remain stable, thereby reducing character garble. 
     Still another advantage of the invention is that the system is flexible and can be easily modified. For example, in a software implementation, a programmer can reprogram the processor  220  to filter out any desired frequency, thereby avoiding costly field time associated with replacing existing equipment. 
     In this disclosure, there is shown and described only the preferred embodiments of the invention, but, as aforementioned, it is to be understood that the invention is capable of use in various other combinations and environments and is capable of changes or modifications within the scope of the inventive concept as expressed herein. 
     For example, the present invention has been described with the example of a TDD modem transmitting signals having frequencies of 1150 Hz (sync tone), 1400 Hz and 1800 Hz (1s and 0s). The present invention may also be used to filter signals having other frequencies. For example, if standards associated with TDD devices change or a particular TDD device transmits signals having other frequencies, the filter  190  may be configured to block out the desired frequencies. In addition, if the standard frequencies associated with transmissions from a TDD/TTY modem in another country is different than those discussed above, the filter  190  may be adjusted to filter the desired frequencies. 
     In addition, the present invention has been described with the example of a hearing-impaired party initiating a telephone call to a hearing party. The acts described in relation to FIG. 3 are similarly applicable if the hearing party initiates the call to a hearing-impaired party.