Abstract:
A method of communicating speech across a communication link using very low digital data bandwidth is disclosed, having the steps of: translating speech into text at a source terminal; communicating the text across the communication link to a destination terminal; and translating the text into reproduced speech at the destination terminal. In a preferred embodiment, a speech profile corresponding to the speaker is used to reproduce the speech at the destination terminal so that the reproduced speech more closely approximates the original speech of the speaker. A default voice profile is used to recreate speech when a user profile is unavailable. User specific profiles can be created during training prior to communication or can be created during communication from actual speech. The user profiles can be updated to improve accuracy of recognition and to enhance reproduction of speech. The updated user profiles are transmitted to the destination terminals as needed.

Description:
REFERENCE TO RELATED APPLICATIONS 
   Not Applicable 
   FIELD OF THE INVENTION 
   The invention relates to the communication of speech over digital networks using very low data bandwidth. Specifically, the inventive method translates speech into text at a source terminal, communicates the text across the communication link to a destination terminal, and translates the text into reproduced speech at the destination terminal. 
   BACKGROUND OF THE INVENTION 
   Telephony communications are increasingly being communicated across digital networks. As a result, it is becoming increasingly desirable to communicate voice over these networks too. Presently, this is accomplished by using Voice over Packet (VoP) systems that compress the voice in accordance with an International Telecommunication Union (ITU) standard. After being conveyed across the digital network, the voice packets are decompressed and used to reproduce a signal at the destination terminal which attempts to closely match the original signal. This solution significantly reduces the required bandwidth while maintaining high voice quality. For example, an uncompressed voice signal requires a bandwidth of 64,000 bits per second (bps). A compressed version of this same voice signal may be communicated with as little as 8,000 bps while still preserving the toll quality of the telephone call. 
   Each compression of an audible signal, which reduces the necessary bandwidth, also reduces the resolution of the signal and causes some distortion. A substantial bandwidth reduction below 8,000 bps may not be possible using prior art methods, without greatly affecting the quality of the voice signal. 
   SUMMARY OF THE INVENTION 
   The inventive method uses voice recognition software to translate spoken words into digitally coded text. The text is transmitted over the digital network instead of the voice signal. When the text arrives at the destination terminal, it is converted back into speech by voice recognition software. The present invention provides a means to communicate a voice signal with as little as 140 bps. 
   In one embodiment, a default voice is used by the destination terminal to reproduce the spoken words. However, the destination terminal may have a database of the speaker&#39;s voice profile so that the reproduced voice sounds like the voice of the original speaker. If this database does not exist at the destination terminal, it is gradually transmitted to the destination terminal during the course of the telephone conversation. Once the speaker&#39;s voice profile is completely communicated, the voice profile used by the destination terminal transitions from the default profile to the speaker&#39;s profile. 
   A voice profile for a speaker is can be initially generated during training of the system or can be generated during one or more conversations. Training allows for voice recognition and allows the system to build a speaker voice profile which not only enables recognition but provides voice for more natural playback at the destination. The voice profile can be created by having the speaker read text provided by the voice recognition software prior to a telephone call or through recognition and correction of speech of the user during a conversation. The software may automatically create the voice profile during a telephone conversation and store and/or transmit it as it is generated or after completion. The voice profile for a user does not have to remain static after its initial creation, it can be improved and refined as the speaker uses the system and adds to the stored vocabulary and speech. At some level of use, the system can accommodate several alternative pronunciations of words to reflect different intonations or inflections of the speaker which can then be reproduced at the destination to enhance the conversation quality. The recognition software can select between the various intonations of the word to be reproduced based upon the recognition of the current pronunciation of the words in the speaker&#39;s present conversation. 
   The present invention teaches a method of communicating speech across a communication link using very low digital data bandwidth, having the steps of: translating speech into text at a source terminal; communicating the text across the communication link to a destination terminal; and translating the text into reproduced speech at the destination terminal. The primary advantage of this invention is the significant reduction of bandwidth it requires to communicate speech across a digital network and the elimination of distortion which can result from compression or packet loss. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Preferred embodiments of the invention are discussed hereinafter in reference to the drawings, in which: 
     FIG.  1 —illustrates a process flow executed by the source terminal of either one of two idealized unidirectional links of a bi-directional telephony link; 
     FIG.  2 —illustrates a process flow executed by the destination terminal in association with the process flow of  FIG. 1 ; 
     FIG.  3 —illustrates a means for conveying the speaker&#39;s voice profile to the destination terminal so that the speech reproduced at the destination terminal sounds like the speech of the original speaker; 
     FIG.  4 —illustrates the process executed by the destination terminal when the process of  FIG. 3  is executed by the source terminal; and 
     FIG.  5 —illustrates an embodiment of the invention that creates the speaker&#39;s voice profile as the speaker communicates speech through a telephony link. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Although a telephony link provides bi-directional communication between the users, the bi-directional link may be described as two separate links. These links are commonly referred to as the forward and reverse links. Each link has a communication medium that interconnects a source and a destination terminal. The source terminal communicates user speech to the destination terminal. Therefore, the source terminal for the forward link serves as the destination terminal for the reverse link. 
     FIG. 1  illustrates a process flow  1  executed by the source terminal of either one of two unidirectional links of a bi-directional telephony link and  FIG. 2  illustrates the associated process flow  5  executed by the destination terminal. As a user&#39;s speech is provided to the source terminal, portions of the speech are sampled and converted  2  to text by voice recognition software. Although throughout the disclosure the information about the content of the speech is described as text, it is not necessary that the speech be converted to text, as any symbolic representation of speech can be used. For instance, each word can be represented by a single digital code instead of a combination of codes which each represent a letter. The important aspect of the invention is that a representation of a word can be communicated with substantially less bandwidth than a digital encoding of the sound of the word. 
   The textual representation of the speech portion is digitally encoded and communicated  3  to the destination terminal. After each speech portion has been sampled, converted to text, and communicated to the destination terminal, the process  1  determines  4  whether the communication link has terminated. If the link is terminated, the process  1  ends. Otherwise, the process  1  samples the next consecutive portion of the speech and converts  2  this portion to text. The most recently converted text is communicated  3  to the destination terminal and the process  1 , again, determines  4  whether the link has terminated. The sequence of converting  2  the next consecutive portion of the received speech to text and then communicating  3  the converted text to the destination unit is repeated until the link is terminated. Process  1  is begun anew when a link is established. 
   For the purpose of simplifying the description and process flowcharts, a link termination, as used in this disclosure, may be any form of momentary or permanent discontinuance of the speaker&#39;s speech or of the telephony link. For example, the link termination may be a pause in the speaker&#39;s conversation. In these instances, process  1  is renewed when the speaker&#39;s next vocal sound is uttered. In an exemplary embodiment, audio processing software can be used to distinguish between speech and background noise to identify pauses. or breaks in speech. Alternatively, the link termination may be the end of the telephony link and process  1  is not renewed until a new telephony link is established. 
   While the source terminal executes process  1 , the destination terminal executes process  5 . Process  5  begins by receiving  6  an individual portion of the communicated text from the source terminal. The received  6  portion of text is converted  7  to speech using the default speech profile of the destination terminal. The speech that is reproduced at the destination terminal has the vocal sound of the person whose voice served as the model for the speech profile, rather than the sound of the speaker. This reproduced speech is conveyed  8  to the listener before process  5  determines  9  whether the link has terminated. If the link has terminated, process  5  ends. Otherwise, the steps of the process  5  are re-executed for the next consecutive portion of text received from the source terminal. The sequence of receiving  6  the next portion of text, converting  7  the received text to speech, and outputting  8  the reproduced speech is repeated until the link terminates. Process  5  is renewed when a link is established. 
     FIG. 3  illustrates an embodiment of the method that provides a means for conveying the speaker&#39;s own natural voice profile to the destination terminal so that the speech reproduced at the destination terminal sounds like the speech of the original speaker. Process  20  begins by determining  21  whether the speaker&#39;s voice profile exists at the source terminal. If the profile does not exist, it is created  22  by having the speaker read text provided by the voice recognition software before the link is established. Once the speaker&#39;s voice profile is created  22 , it may be stored to memory and subsequently accessed without having to be re-created for every instance of an established link. The profile can also be periodically updated based on additional words spoken and stored as the system is used. Next, process  20  determines  23  whether the speaker&#39;s voice profile exists at the destination terminal. This determination may be made according to any known method. As an exemplary method, the source terminal conveys the profile identification to the destination terminal and the latter terminal responds with an indication of whether it has a copy of the profile. 
   If the destination terminal has a copy of the speaker&#39;s voice profile, process  20  repeatedly executes the same steps executed by process  1 , in  FIG. 1 . First, a portion of the speech provided to the source terminal is sampled and converted  24  to text. Next, the text is communicated  25  to the destination terminal. Lastly, a determination  26  is made as to whether the link has terminated. If so, the process  20  ends. Otherwise, the sequence of converting  24  the next consecutive portion of the received speech to text and then communicating  25  the converted text to the destination unit is repeated until the link is terminated. Process  20  is begun again when a link is re-established. 
   If the destination terminal does not have a copy of the speaker&#39;s voice profile, as determined in step  23 , process  20  communicates the voice profile to the destination terminal. Beginning with step  28 , process  20  samples a portion of the speech and converts  28  it to text. Thereafter, the converted text and a portion of the speaker&#39;s voice profile are communicated  29  to the destination terminal. Next, a determination is made whether the speaker&#39;s voice profile has been completely communicated  30  to the destination terminal. If not, a determination  31  is made whether the link has terminated. Process  20  ends when the link is terminated. If the link has not terminated, then the next consecutive portion of the received speech is sampled and converted  28  to text. Both the converted text and the next remaining portion of the voice profile are communicated  29  to the destination terminal and another determination  30  is made whether the speaker&#39;s voice profile has been completely communicated to the destination terminal. Process steps  28 – 31  are repeated until either the link is terminated or the speaker&#39;s voice profile has been completely communicated to the destination terminal. If the link terminates before the voice profile is completely communicated, only the un-sent portion of the profile need be communicated when the link is re-established for this same speaker. Once a determination  30  is made that the voice profile has been completely communicated to the destination terminal, the flow of process  20  transfers to step  26  where a determination is made whether the link has terminated. For the remaining existence of the link, the converted text will be communicated to the destination terminal without a portion of the voice profile being sent also. 
     FIG. 4  illustrates the process  40  executed by the destination terminal when process  20 , of  FIG. 3 , is executed by the source terminal. Process  40  begins by determining  41  whether the destination terminal has a copy of the speaker&#39;s voice profile. If so, the source terminal is informed  42  of this fact. Thereafter, the steps  43 – 46  of process  40  are nearly identical to steps  6 – 9  of process  5 , which is illustrated in  FIG. 2 . First, the destination terminal receives  43  the text communicated to it by the source terminal. Then, the text is converted  44  to speech using the speaker&#39;s voice profile. The reproduced speech has the vocal characteristics of the original speaker when it is output  45  by the destination device. After each portion of the received text is converted into a reproduction of the original speech, a determination  46  is made whether the link has terminated. If so, process  40  ends. Otherwise, the next portion of text received from the source terminal is similarly received  43 , converted  44  to speech using the speaker&#39;s voice profile, and output  45  as a reproduction of the original speech in the speaker&#39;s voice. Steps  43 – 45  are repeated until the link terminates. 
   If a determination is made in step  41  that the speaker&#39;s voice profile does not exist at the destination terminal, then the flow of process  40  transfers to the branch of steps comprising steps  48 – 53 . In step  48 , the destination terminal informs the source terminal that it does not have a copy of the speaker&#39;s voice profile. Next, the process repeatedly executes a set of steps  49 – 51  that is similar to the set of steps  6 – 8  in process  5  of  FIG. 2 . With regard to process  40 , however, the destination terminal receives  49  not only the text communicated by the source terminal but also the communicated portion of the speaker&#39;s voice profile. The portion of the received voice profile is stored to memory by the destination device and the received text is converted  50  to speech using the default voice profile of the destination terminal. The reproduced speech has the voice characteristics of the person whose voice was used to model the voice profile, rather than the speaker&#39;s voice characteristics. As the text is converted to speech, it is conveyed  51  to the listener. Once the speech portion is output, a determination  52  is made whether the speaker&#39;s profile has been completely received from the source terminal. If so, all text subsequently received within the duration of the link will be converted to speech using the speaker&#39;s voice profile. Therefore, an affirmative determination in step  52  leads the process out of the branch of steps  49 – 53  and into the branch of steps  42 – 46 , the destination terminal informs the source terminal that the profile has ben fully received and the speaker&#39;s voice profile is used for the speech conversion, steps  43 – 46 . 
   If a determination is made in step  52  that the speaker&#39;s profile has not been fully received from the source terminal, then a determination  53  is made whether the link has terminated. If so, process  40  ends. Since the received portion of the speaker&#39;s voice profile has been stored to memory by the destination terminal, only the remaining portion of the profile need be communicated to the destination terminal when the link is re-established for the same speaker. If the link has not terminated, as determined in step  53 , the sequence of steps  49 – 51  is repeated until either the speaker&#39;s voice profile is completely received or the link terminates. This sequence comprises receiving the communicated text and speaker profile portions  49 , storing the received portion of the speaker profile to memory, converting the received text to speech  50  using the default voice profile, and outputting the reproduced speech  51 . 
     FIG. 5  illustrates an embodiment of the invention that creates the speaker&#39;s voice profile as the speaker communicates speech through the link. Process  60  begins by determining  61  whether the speaker&#39;s voice profile exists at the destination terminal. If the voice profile exists at the destination terminal, a portion of the incoming speech provided by the speaker is sampled and converted  62  to text by voice recognition software. The converted text is communicated to the destination terminal before a determination  54  is made whether the link has terminated. If the link has terminated, process  60  ends. If the link has not terminated, the next consecutive portion of the speaker&#39;s incoming speech is sampled and converted  62  to text. Again, the converted text is communicated  63  to the destination terminal before a determination  64  is made whether the link has terminated. This sequence of sampling and converting  62  to text the next consecutive portion of incoming speech, communicating  63  the converted text, and determining  64  whether the link has terminated is repeated until the link terminates. 
   If a determination is made that the destination device does not have a copy of the speaker&#39;s voice profile in step  61 , a determination  66  is made whether the source terminal has a copy of the profile. If so, process  60  executes a branch of steps  67 – 70 , to communicate the speaker&#39;s voice profile, that is nearly identical to the branch of steps  28 – 31  in process  20 , as illustrated in  FIG. 3 . Process  60  samples a portion of the speaker&#39;s incoming speech and converts  67  it to text. Thereafter, the converted text and a portion of the speaker&#39;s voice profile are communicated  68  to the destination terminal. Next, a determination is made whether the speaker&#39;s voice profile has been completely communicated  69  to the destination terminal. If not, a determination  70  is made whether the link has terminated. Process  60  ends when the link is terminated. If the link has not terminated, then the next consecutive portion of the speaker&#39;s incoming speech is sampled and converted  67  to text. Both the converted text and the next remaining portion of the voice profile are communicated  68  to the destination terminal and another determination  69  is made whether the speaker&#39;s voice profile has been completely communicated to the destination terminal. Process  60  steps  67 – 70  are repeated until either the link is terminated or the speaker&#39;s voice profile has been completely communicated to the destination terminal. If the link terminates before the voice profile is completely communicated, only the portions of the profile that were not communicated will be communicated when the link is re-established for this same speaker. Once a determination  69  is made that the voice profile has been completely communicated to the destination terminal, the flow of process  60  transfers to step  64  where a determination is made whether the link has terminated. For the remaining period of the link, the converted text will be communicated to the destination terminal without a portion of the voice profile being sent along with it. 
   If the speaker&#39;s voice profile does not exist at the destination terminal, as determined by step  66 , steps  71 – 75  are repeatedly executed until either the speaker&#39;s profile has been created and completely communicated to the destination terminal or the link is terminated. Beginning with step  71 , a portion of the speaker&#39;s speech is sampled and converted  71  to text by voice recognition software. The sampled portion of the speech is also used by the voice recognition software to generate  72  the speaker&#39;s voice profile. Both the converted text and any portion of the voice profile available for conveyance are communicated  73  to the destination terminal. It is not necessary to convey portions of the speaker profile as they are created to be within the scope of the invention. It may be advantageous in some implementations to delay transmission until the speaker&#39;s profile is developed to a certain extent or until it is fully developed. 
   Next, a determination  74  is made whether the speaker&#39;s voice profile has been completely generated based upon the voice sampling. If so, no further generation of the speaker&#39;s voice profile will be made, for the remaining period of the communication link. The process  60  flow branches to step  69  for a determination of whether the speaker&#39;s profile has been fully received at the destination. If the speaker profile has been completely received, the process flows through blocks  67 – 70 . Once the profile is fully received, process  60  repeatedly samples and converts  62  the next incoming portion of the speaker&#39;s incoming speech to text, communicates  63  the converted text to the destination terminal, and re-evaluates  64  whether the link has terminated. 
   If a negative determination is made in step  74  as to whether the speaker&#39;s voice profile has been completely communicated, a determination  75  is made whether the link has terminated. If so, process  60  is terminated. Any portion of the speaker&#39;s voice profile that was not completely generated  72  and communicated  73  to the destination terminal prior to a link termination may be generated and communicated when the next link between these source and destination terminals is established for this speaker. If a negative determination is made in step  75  regarding the termination of the link, the next consecutive portion of the speaker&#39;s incoming speech is sampled and converted  71  to text. This next sample is used to continue generating  72  the speaker&#39;s voice profile. The available converted text and portion of the generated  72  voice profile are communicated  73  to the destination terminal before another determination is made whether the voice profile has been completely generated. The sequence of sampling the next consecutive portion of the speaker&#39;s incoming speech and converting  71  it to text, continuing the generation  72  of the speaker&#39;s voice profile, and communicating  73  the converted text and the additional voice profile information is repeated until either the link is terminated or the speaker&#39;s voice profile has been completely generated. 
     FIG. 4  illustrates the process  40  executed by the destination terminal when process  60 , of  FIG. 5 , is executed by the source terminal. The same process  40  is executed by the destination terminal when either of processes  20  or  60  are executed by the source terminal. 
   The speaker&#39;s profile may be periodically updated as use of the system will add words, phrases, proper names, inflections intonations and the like to the database of the user. The updated profile can be used by the source terminal to increase the accuracy of speech recognition. Further, the updated profile can be periodically transmitted to the destination terminal to update a previously transmitted speaker profile to allow for enhanced playback. Updating can take place during a subsequent conversation between the source and destination terminals or can take place as part of a separate transfer connection. 
   Because many varying and different embodiments may be made within the scope of the inventive concept herein taught, and because many modifications may be made in the embodiments herein detailed in accordance with the descriptive requirements of the law, it is to be understood that the details herein are to be interpreted as illustrative and not in a limiting sense.