Patent Publication Number: US-2002013708-A1

Title: Speech synthesis

Description:
FIELD OF THE INVENTION  
       [0001] This invention relates to speech synthesis and audible reading of text by artificial means.  
       BACKGROUND OF THE INVENTION  
       [0002] A significant portion of communications has shifted from telephone calls and paper based messages to text messages in electronic form transmitted electronically, such as e-mail. Text messages in electronic form are received and displayed on computer displays and on other electrical and electronic displays. Using e-mail to prepare and send text messages is popular because it provides quick delivery to a potentially large number of recipients and can be prepared by computer, to which many people have access. In addition text messages can be readily stored and then read by their recipients when it is convenient.  
       [0003] Examples of text messages include e-mail text messages for display on computers and SMS (short message service) messages for display on mobile telephones. As digital convergence occurs, it is now becoming common for messages sent by one type of transmitting electronic device to be received by another type of electronic device. For example, e-mail text messages sent by a computer can be received and displayed by mobile telephones. Equally, mobile telephones can transmit e-mail text messages to computers or to other mobile telephones.  
       [0004] When such text messages are only sent from computer to computer, this causes no problems in their reading, even for relatively long text messages. This is because computer displays are large enough to present such text messages conveniently and because computer users are typically stationary and able to direct their attention to their computer displays. It is becoming common for text messages to be received by mobile communications devices such as mobile telephones. However, since these devices usually have displays which are small enough to enable the devices to be comfortably carried by a user it can be difficult for a user to read received text messages comfortably, especially if there is a large amount of text, Furthermore, with mobile communications devices, there can be problems in reading such text messages, for example whilst the user is travelling in a car or carrying out any other activity requiring the user&#39;s gaze to be directed elsewhere.  
       [0005] Due to these difficulties in delivery of text messages, information systems have been developed which are able to record verbal messages or to convert text into speech by means of speech synthesis.  
       [0006] In speech synthesis, the quality of the speech produced is highly dependent on the number of bytes used in a speech synthesis template which characterises the synthesised speech. Good quality speech synthesis may require a large amount of data for the speech synthesis template. In addition, a significant amount of computing power is required to produce the speech synthesis template. Such requirements are difficult to accommodate with mobile telephones. Moreover, generating the speech synthesis template is a time consuming task to perform for the speaker whose speech is to be synthesised. As a consequence, a device will usually only contain one speech synthesis template or at maximum a few speaker&#39;s speech synthesis templates to generate synthesised speech.  
       [0007] Japanese patent publication 11-219278 discloses a system in which users are able to have a virtual presence in a three-dimensional virtual space. If a user wishes to speak to another user, the user&#39;s speech is recognised, converted into a character-based message and then the character-based message is transmitted. On receipt, the character-based message is synthesised into speech and the synthesised speech is played to the other user. The speech synthesis is improved by applying tone and volume control in order to simulate a virtual distance between the speaker and the listener in the virtual space.  
       SUMMARY OF THE INVENTION  
       [0008] According to a first aspect of the invention there is provided a communications device comprising:  
       [0009] a memory for storing a speech synthesis template for synthesizing speech;  
       [0010] a message handler for sending a text message together with an identifier identifying the source of the text message to a recipient of the text message; and  
       [0011] a speech synthesis template handler for sending a copy of the speech synthesis template so that it is accessible by the recipient of the text message.  
       [0012] Preferably the communications device communicates with a communications network. It may communicate with other communications devices, such as the recipient, via the communications network.  
       [0013] Preferably the communication device comprises a message generator for generating the text message.  
       [0014] Preferably the speech synthesis template is sent to the recipient of the text message.  
       [0015] Preferably the speech synthesis template is specific to a designated user of the communications device in order to provide synthesised speech which sounds like the voice of the designated user.  
       [0016] Preferably the speech synthesis template handler is arranged to send the copy of the speech synthesis template to the recipient of the text message on demand. This may be as a consequence of demand by the recipient or demand by the network.  
       [0017] Preferably the communications device stores a record of the speech synthesis templates which have been sent and the recipient devices to which they have been sent. The communication device may comprise a checker which, on sending the text message, checks whether the speech synthesis template has already been sent to, or received by, the recipient. If the speech synthesis template has already been sent to, or received by, the recipient, the speech synthesis template handler may be arranged to send the speech synthesis template. This may happen automatically on sending to the text message.  
       [0018] Preferably the communications device has a request receiver for receiving a speech synthesis template sending request and the speech synthesis template handler is arranged to send the copy of the speech synthesis template to the recipient of the text message in response to the speech synthesis template sending request. The request may be sent by a recipient or by the communications network. Preferably the receiver is arranged to detect from the request a destination for the requested speech synthesis template and the speech synthesis template handler is arranged to send the speech synthesis template to the detected destination.  
       [0019] Preferably the communication device is a mobile device. Alternatively the communication device is in a fixed network. It may be a mobile telephone, a PDA (personal digital assistant) or a mobile, portable computer such as a laptop computer or a network terminal.  
       [0020] According to a second aspect of the invention there is provided a communications device comprising:  
       [0021] a memory for storing a speech synthesis template for synthesising speech;  
       [0022] a message receiver for receiving a text message together with an identifier identifying the source of the text message; and  
       [0023] a speech synthesis template receiver for receiving a copy of the speech synthesis template corresponding to the source of the text message for artificially reading the text message using the copy of the speech synthesis template received.  
       [0024] According to a third aspect of the invention there is provided a communications system comprising a communications device and a network, the communications system comprising:  
       [0025] a memory for storing a speech synthesis template for synthesising speech;  
       [0026] a message handler for sending a text message together with an identifier identifying the source of the text message to a recipient of the text message; and  
       [0027] a speech synthesis template handler for sending a copy of a speech synthesis template to the recipient of the text message.  
       [0028] Preferably the network comprises a database for storing a plurality of speech synthesis templates. The database may store identifiers which correspond to the speech synthesis template. The speech synthesis templates may have been received from communications devices. Preferably the network comprises a speech synthesis template handler for sending the copy of the speech synthesis template to the communications device. This may be in response to a request for the speech synthesis template or may be at the initiative of the network or a server.  
       [0029] According to a fourth aspect of the invention there is provided a speech synthesis template server for storing a plurality of speech synthesis templates in a communications network, the server comprising:  
       [0030] a memory for storing speech synthesis templates for synthesising speech;  
       [0031] a memory for storing identifiers which identify the source of the speech synthesis templates; and  
       [0032] a speech synthesis template handler for sending a copy of a speech synthesis template to a communications device.  
       [0033] Preferably the server comprises a database for storing the plurality of speech synthesis templates. The speech synthesis templates may have been received from communications devices. Sending the copy of the speech synthesis template may be in response to a request for the speech synthesis template or may be at the initiative of the network or a server.  
       [0034] Preferably the communications device is the recipient of a text message which has been received from a party which is the source of a particular speech synthesis template.  
       [0035] According to a fifth aspect of the invention there is provided a method of converting a text message into synthesised speech, the method comprising the steps of:  
       [0036] storing a speech synthesis template for synthesising speech;  
       [0037] sending a text message together with an identifier identifying the source of the text message to a recipient of the text message; and  
       [0038] sending a copy of the speech synthesis template to the recipient of the text message.  
       [0039] According to a sixth aspect of the invention there is provided a method of converting a text message into synthesised speech, the method comprising the steps of:  
       [0040] storing a speech synthesis template for synthesising speech;  
       [0041] receiving a text message together with an identifier identifying the source of the text message;  
       [0042] receiving a copy of the speech synthesis template corresponding to the source of the text message; and  
       [0043] reading artificially the text message using the copy of the speech synthesis template received.  
       [0044] According to a seventh aspect of the invention there is provided a method of handling a plurality of speech synthesis templates, the method comprising the steps of:  
       [0045] receiving a text message together with an identifier identifying the source of the text message to a recipient of the text message;  
       [0046] receiving a speech synthesis template for synthesising speech; and  
       [0047] sending a copy of the speech synthesis template to the recipient of the text message.  
       [0048] Preferably the method comprises the step of storing the speech synthesis template. The speech synthesis template may be stored in the network. It may be stored in a server. It may be stored in a server according to the third aspect of the invention.  
       [0049] Preferably the method comprises the step of storing identifiers which correspond to the speech synthesis templates. Preferably, the speech synthesis templates may have been received from communications devices. Sending copies of the speech synthesis templates may be in response to a request for them by communications devices or by a network.  
       [0050] According to an eighth aspect of the invention there is provided a method of handling a plurality of speech synthesis templates, the method comprising the steps of:  
       [0051] storing a plurality of speech synthesis templates for synthesising speech;  
       [0052] storing identifiers which identify sources of the speech synthesis templates;  
       [0053] receiving an identifier; and  
       [0054] sending a copy of a speech synthesis template corresponding to the identifier to the recipient of a text message.  
       [0055] According to a ninth aspect of the invention there is provided a method of converting a text message into synthesised speech comprising the steps of:  
       [0056] associating a first speech synthesis template for synthesising speech having a first set of speech characteristics with text messages originating from a first specified source;  
       [0057] associating a second speech synthesis template for synthesising speech having a second set of speech characteristics with text messages originating from a second specified source, the first set of speech characteristics being distinguishable from the second set of speech characteristics;  
       [0058] receiving a text message;  
       [0059] checking the source from which the text message originates; and  
       [0060] synthesising speech according to one of the first speech synthesis template and the second speech synthesis template depending on the source from which the text message originates.  
       [0061] Preferably the specified sources identify specific individuals. Alternatively, the specified sources identify groups of individuals. In its most basic form, the groups an be male and female senders of text messages.  
       [0062] Preferably the speech synthesised by the second set of speech characteristics is distinguishable from the speech synthesised by the first set of speech characteristics by a human listener listening to the synthesised speech.  
       [0063] Preferably at least one of the first and second speech synthesis templates is transmitted by a network to a mobile communications device. Preferably the mobile communications device stores at least one speech synthesis template which is transmitted to it.  
       [0064] In radio telecommunications, channel bandwidth is limited and so it is not practical to transmit speech synthesis templates with electronic text messages. However, since recipients often receive electronic text messages again and again from the same people, it may be desirable for a receiving communications device (referred to in the following as a “recipient device”) to have access to (and preferably to contain) speech synthesis templates which are used for synthesising the speech of users regularly sending text messages. In this way, it is not necessary always to send speech synthesis templates for certain speakers since they may already be stored in a device. Furthermore, it may be necessary only to send speech synthesis templates when they are really needed, that is when they are not already held. This is possible if the delivery system, such as a telecommunications network, takes into account cases where a copy of the speech synthesis template is already at the recipient device, or is accessible within the network and does not send the speech synthesis template in such cases. This may apply in the majority of cases.  
       [0065] In another method according to the invention, at least one speech synthesis template is stored in the network and speech synthesis by that speech synthesis template is carried out in the network and the resulting synthesised speech (or code to enable such synthesised speech) is transmitted to the communications device. In this way, it is not necessary for a recipient device to be sent and to store speech synthesis templates.  
       [0066] According to a tenth aspect of the invention there is provided a communications device for converting a received text message into synthesised speech comprising a memory for storing a first speech synthesis template for synthesising speech having a first set of speech characteristics and a second speech synthesis template for synthesising speech having a second set of speech characteristics, the first speech synthesis template being associated with a first specified source and the second memory being associated with a second specified source, the first set of speech characteristics being distinguishable from the second set of speech characteristics, an identifying unit for checking the source from which the received text message originates and speech synthesis means for synthesising speech according to one of the first speech synthesis template and the second speech synthesis template depending on the source from which the received text message originates.  
       [0067] Preferably the identified speech synthesis template is used to generate synthesised speech according to the text message.  
       [0068] Preferably the communications device is a mobile communications device. Alternatively, the communications device is network-based. In an embodiment in which the invention relates to a wireless communication system, this means that the communications device is on the network side of an air interface across which the communications device and a communications network communicate.  
       [0069] According to an eleventh aspect of the invention there is provided a communication system comprising a network and a communications device according to the tenth aspect of the invention.  
       [0070] According to a twelfth aspect of the invention there is provided a computer program product comprising computer program code means for executing on a computer any of the methods of aspects five to nine.  
       [0071] The invention recognises that, in the future, it may be desired to handle text messages in electronic form and present the content of such text messages in synthesised speech rather than in textual form. It may be particularly desirable to synthesise speech which uses a speech synthesis template prepared according to the voice of a user sending the text message, typically by using a sending communications device (referred to in the following as a “sending device”) so that the synthesised speech sounds like the voice of the user sending the text message.  
       [0072] Other aspects of the invention are computer programs comprising readable computer code for carrying out the steps of each of the methods according to the aspects of the invention. Each of the computer programs thus defined may be stored on a data carrier such as a floppy disc, a compact disc or in hardware. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0073] The invention will be described, by way of example only, with reference to the accompanying drawings in which:  
     [0074]FIG. 1 shows an embodiment of a communications system according to the invention;  
     [0075]FIG. 2 shows a flowchart of a first method of the invention;  
     [0076]FIG. 3 shows a flowchart of a second method of the invention;  
     [0077]FIG. 4 shows a flowchart of a third method of the invention;  
     [0078]FIG. 5 shows a flow chart of a fourth method of the invention;  
     [0079]FIG. 6 shows synchronisation of speech synthesis templates; and  
     [0080]FIG. 7 shows another embodiment of a communications system according to the invention. 
    
    
     DETAILED DESCRIPTION  
     [0081] An embodiment of a communications system according to the invention is shown in FIG. 1. The system comprises three main entities: a mobile telecommunications network  130 , a sending device  110  and a recipient device  120 . The sending device and the recipient device are connected to the mobile telecommunications network  130 , They are identical devices and may be mobile communications devices such as mobile telephones. Each device comprises a central processing unit  124  controlling a first memory  111 , a second memory  112  and a third memory  113  and further controlling a radio frequency block  115  coupled to an antenna  116 , The memories  111 ,  112 , and  113  are preferably such that they maintain their contents even if the device runs out of power. In the preferred embodiment the memories in the devices are semiconductor memories such as flash-RAM memories which do not have moving parts. The sending device  110  and the recipient device  120  communicate with the mobile telecommunications network  130  over radio channels.  
     [0082] The mobile telecommunications network  130  comprises a database  132  comprising a plurality of records  133 ,  134 ,  135  and  136  for maintaining speech synthesis templates for a plurality of network users. The database is controlled by a processing unit  131 , which has access to each of the records  133 ,  134 ,  135  and  136 . The database is preferably stored on a mass memory such as a hard disc or a set of hard discs. In combination, the database  132  and the processing unit  131  are part of a speech synthesis template server  137 .  
     [0083] Operation of the communications system will now be described. When a user of a recipient device receives a text message, a choice is presented for the text message either to be shown displayed visually or to be audibly read so that the user can listen to the content of the text message. Of course, the user may elect to use both visual display and audible presentation although usually only one form of presentation is necessary, A default method of visual display is preferred. If the user chooses audible presentation, the recipient device checks the identity of the sender of the text message and then uses a speech synthesis template which is associated with the sender to present the content of the text message in an audible form which corresponds to the voice of the sender. If the speech synthesis template is not located in the recipient device, the recipient device obtains it either from the network or from the sending device via the network. In this way, the user is able to listen to text messages in voices which correspond to the senders of text messages. One advantage of this is that the user can discriminate between text messages depending upon the voices in which they are read or even identify the sender of a text message depending on the voice in which it is read.  
     [0084] When a sending device  110  first sends a text message to the network  130 , the network will need to receive a speech synthesis template appropriate for that sending device  110 . This is a speech synthesis template to generate speech which sounds like the user, or one of the users, of the sending device. The speech synthesis template is therefore sent (i) with the text message, (ii) at a later point in time decided by the sending device  110  or (iii) as a consequence of the network  130  requesting this (either at the time when the text message is received by the network  130  or at a later point in time). The speech synthesis templates are (i) stored by the network, (ii) stored by recipient devices or (iii) stored by the network and by recipient devices. The circumstances under which speech synthesis templates are sent depend on which of the following methods of the invention is being used. It is important to understand that the following methods relate to situations in which some speech synthesis templates may already have been sent by sending devices  110 , received by the network  130  and then stored.  
     [0085] A first method of handling speech synthesis templates will now be described. The sending device  110  keeps a list of recipient devices  120  to which its speech synthesis template has been sent. In fact the sending device may have a primary speech synthesis template and secondary, or associated, speech synthesis templates. When sending a new text message to a particular recipient device  120 , the sending device  110  checks whether the list shows that the recipient device  120  has already received the speech synthesis template. If the speech synthesis template has already been sent, then only the text message is sent. If the speech synthesis template has not already been sent, a copy of the speech synthesis template is attached to the text message and sent with it. When the recipient device  120  receives the speech synthesis template attached to the text message, the recipient device  120  stores it in a speech synthesis template memory. The speech synthesis template memory may be of any suitable kind such as a mass memory, flash-ROM, RAM or a disk/diskette. In case the recipient device  120  appears to have a speech synthesis template but does not, in fact, have it, the recipient device  120  may specifically request that it be sent. The way in which a speech synthesis template may be requested is described in the following.  
     [0086] The first method is shown in FIG. 2.  
     [0087] In a second method of handling speech synthesis templates, the sending device  110  does not send speech synthesis templates with a text message on initial sending of the text message. On receiving a text message which includes an appropriate identifier of the sending device  110 , the recipient device  120  checks to see if an appropriate speech synthesis template for that sending device  110  has already been stored in its memory. If such a speech synthesis template has not been stored, the recipient device  120  requests that a copy of the speech synthesis template be sent. A circumstance in which the speech synthesis template may not be stored any longer is if speech synthesis templates are stored in a speech synthesis template memory (a kind of cache). As new speech synthesis templates are stored in the memory, old speech synthesis templates already stored in the memory are deleted to make space for the newer ones. Alternatively, the least used speech synthesis templates may be deleted rather than the oldest ones, One or more old or little-used speech synthesis templates may be deleted at a time. Alternatively, or additionally, speech synthesis templates may have associated with them a lifetime and may be deleted when the lifetime expires. This speech synthesis template management system may be applied to the first or to any of the subsequent methods.  
     [0088] In this method a protocol is provided to enable a sending device  110  to be identified to the recipient device  120  and for the recipient device  120  to request the sending device&#39;s speech synthesis template and download it from the recipient device  120 .  
     [0089] The second method is shown in FIG. 3.  
     [0090] In a third method of handling speech synthesis templates, the functionality is similar to the second method, However, rather than only being stored in the sending and recipient devices, speech synthesis templates are stored on the speech synthesis template server  137 . Speech synthesis templates are requested from the speech synthesis template server by a recipient device  120  rather than being requested from a sending device  110 . To maintain the database in the speech synthesis template server there are several options. The network  130  can request a speech synthesis template in relation to the first text message which is sent by a sending device  110 . Alternatively, the speech synthesis template server  137  can request the speech synthesis template (on demand) so that the first time the speech synthesis template is requested by a recipient device  120 , the speech synthesis template server  137  further requests the appropriate speech synthesis template from the sending device  110  which sends a suitable copy. The speech synthesis template server  137  receives the copy, stores its own copy in its memory for future use and then sends a copy to the recipient device  120 . In this way, the sending device  110  need not transmit the speech synthesis template over the radio path more than once. Furthermore, once the synthesis template has been stored in the speech synthesis template server  137 , it can be transferred within one or more wired or mobile networks, for example the Internet.  
     [0091] The network  130  can intercept requests to sending devices  110  for speech synthesis templates and provide such templates if it already has them. If it does not already have them, it can allow the requests to continue on to the sending devices  110 .  
     [0092] The third method is shown in FIG. 4.  
     [0093] In a fourth method of handling speech synthesis templates, speech synthesis templates do not need to be transmitted to the recipient devices  120  at all. In this method, speech synthesis templates are transmitted to the network  130  from the sending devices  110  and then stored in the network  130 . On requesting a text message to be presented in the form of synthesised speech, the necessary speech synthesis is carried out in the network  130  and synthesised speech is transmitted from the network to the recipient in suitably encoded form. The speech synthesis templates may be transmitted to the network  130  on transmission of a text message, or at the initiative of the sending device  110  or the network  130  as is described in the foregoing.  
     [0094] The fourth method is shown in FIG. 5.  
     [0095] In its first and second methods, the invention may be implemented by software executed by the sending and recipient devices which controls a speech synthesis application in the sending device  110 . This application manages a communications device&#39;s own speech synthesis template and speech synthesis templates which have been received from other communications devices and stored. The recipient device  120  includes a corresponding speech synthesis application. In the third method, the speech synthesis template server  137  has appropriate hardware in the network  130  to buffer the speech synthesis templates. This may be realised either within the network  130  or within a server which is attached to a fixed telecommunications network or to a communications network such as the Internet. In the fourth method, all of the functionality concerning speech synthesis templates and speech synthesis is within the network. The communications devices only require the ability to transmit and receive text messages and to request synthesised presentation of the text messages. The third method is preferred over the first and second methods since it minimises the amount of data which needs to be transferred. On the other hand, the first and second methods do not require speech synthesis templates to be stored in the network  130  and might be preferred by people who prefer that their speech synthesis templates are not available to the public. However, it is possible to provide encryption protection in these cases as is described in the following. The first and second methods do not require support from the network  130  other than the forwarding of speech synthesis templates. The fourth method enables receiving of spoken messages even with devices which are not able to receive speech synthesis templates.  
     [0096] For those methods in which the speech synthesis templates are transmitted to the communications devices, it should be understood that this does not have to be at the time that the text message is transmitted or is to be presented to the user of the recipient device  120 . Initially a text message could be read out using a default speech synthesis template, perhaps the speech synthesis template for the user of the recipient device  120 , and a new speech synthesis template could be received at a more appropriate time, for example at a off-peak time to preserve bandwidth. The recipient device  120  can automatically retrieve the new speech synthesis template at an appropriate time, for example when the recipient device  120  is not being used. Alternatively, the recipient device  120  may request an off-peak delivery from the network  130  so that the network  130  sends the requested speech synthesis template at its own convenience. The speech synthesis template may be segmented on transmission and re-assembled on reception.  
     [0097] In all of the preceding embodiments distribution of speech synthesis templates may occur as a result of a synchronisation operation. The devices  110  and  120  may, from time to time, not be in communication with the network  130 , for example, they may be switched off or set to be in an off-line operation mode. When communication is re-established, it may be desirable to synchronise data held in the devices with data held in the network  130 .  
     [0098] When synchronisation is started, for example when calendar items are being synchronised, at the same time devices connected to the network  130  can request from the speech synthesis template server  137  new templates. This may be done if it is noticed that any of the devices hold messages, for example which have just been received from a sending device or sending devices, for which a template is not held. Such synchronisation can occur by use of synchronisation mark-up language (SyncML) as will be understood by those skilled in the art. The speech synthesis templates may be taken from the “library” of speech synthesis templates of the third aspect of the invention.  
     [0099] The templates may be downloaded from any synchronisation source available to the user, for example by using a local connection (such as hardwired, low power radio frequency, infra-red, Bluetooth, WLAN) with the user&#39;s PC. In this way, expensive and time-consuming over-the-air downloads are avoided.  
     [0100]FIG. 6 shows synchronisation of speech synthesis templates according to the invention. A recipient device receives text messages such as e-mails over the air. Subsequently, the device is plugged into a desktop stand which has a hardwired connection to the users PC. As a part of normal data synchronization, for example updating calendar data from an office calendar, the recipient device receives those speech synthesis templates which it requires to synthesise the newly received text messages into speech.  
     [0101] As the recipient device requests synchronization from a synchronization server, it sends in the request data concerning those speech synthesis templates which it requires. The required speech synthesis templates are determined by comparing the newly received e-mails contained by the recipient device to the speech synthesis templates held by the recipient device. The synchronization server processes the request by the recipient device and provides the speech synthesis templates either from its own memory or from an external server.  
     [0102] In addition to adding speech synthesis templates, synchronisation may involve removal of one or more templates in order to free some memory of the device being synchronised. Determination of which speech synthesis templates are required is carried out by the recipient device in the process of determining the synchronisation data set. The recipient device may intelligently decide the data set to be synchronised based on the relevance of the data to be synchronised. The relevance of a particular speech synthesis template would, for example, be determined by the number of e-mails received from the person whose voice the speech synthesis template represents.  
     [0103]FIG. 7 shows a communications system for handling speech synthesis templates. It provides a way for acquiring speech synthesis templates and storing them on a speech synthesis template server.  
     [0104]FIG. 6 has features in common with FIG. 1 and corresponding reference numerals have been applied to features which are common to both systems. Speech synthesis templates are stored in the speech synthesis template server  137 . However, rather than only being obtained from sending devices  110 , they are obtained from speech synthesis template creation entities  160  via a network  158  such as an intranet or the Internet.  
     [0105] The speech synthesis template creation entities  160  are network terminals equipped with speech synthesis template creation software. These entities may comprise personal computers. A single entity  160  comprises audio capture equipment  160  for audio capture. The audio capture equipment has a microphone and an associated analogue-to-digital converter for digitising captured speech. Digitised captured speech is stored on a hard drive  162 . Speech synthesis template creation software  165  creates a speech synthesis template by analysing the digitised captured speech stored on the hard drive  162 . The software  165  may also be stored in the hard drive  162 .  
     [0106] The entity  160  also comprises a network adaptor  163  to enable connection of the entity  160  to the network and a user interface  164 . The user interface  164  enables a user to have access to and to operate the software  165 .  
     [0107] The operation of the communications system will now be described. Typically the network terminal  160  is a user&#39;s personal computer. If a user desires to make his speech synthesis template generally accessible (so that it can be obtained by recipients of text messages from him), the user activates the software  165  and follows various speaking and teaching exercises which are required. This usually involves repetitions of sounds, words and phrases. Once a speech synthesis template has been created, the user can send it to the speech synthesis template server  137 . This server is typically under control of the operator of the network  130 .  
     [0108] Alternatively the network terminal  160  is provided by and under the control of a service provider. In this case, the user may generate a speech synthesis template when it is convenient or necessary. For example, one convenient time to generate a speed synthesis template is on establishment of a new connection to the network  130 , for example on purchasing a mobile telephone.  
     [0109] Once the server  137  contains speech synthesis templates, they may be obtained by recipients of text messages who request a corresponding speech synthesis template so that the text message may be read out. Each time the server  137  is used to provide a speech synthesis template, a charge may be levied against the party requesting the speech synthesis template.  
     [0110] It will be appreciated that a common purpose of all of the methods is to send the speech synthesis templates only where it is necessary, for example at the initiative of the network  130  or in response to a demand from a communications device.  
     [0111] A convenient way of generating the speech synthesis templates will now be described. This involves teaching the speech synthesis templates the specific characteristics of the voice to be synthesised so that it can be reproduced.  
     [0112] In one embodiment, the communication devices generate text messages by voice recognition. In order to preserve memory space, a communication device has a combined speech recognition/synthesis application program. This application program is able to recognise the speech and convert it into text. Although speech recognition is already known from the prior art (requiring the use of either speaker dependent or speaker-independent speech recognition templates), the invention proposes that pre-existing speech recognition functionality is used additionally for converting text into speech. In this way, using pre-existing speech recognition templates, the user of a communications device would not have to spend time teaching the device to recognise and to synthesise his speech as an a individual and separate activity but such teaching can be combined both for speech recognition and for speech synthesis.  
     [0113] In situations in which speech recognition is used to produce the text messages rather than, say, typing, when the sending device  110  is learning to recognise the sender&#39;s speech, in order to generate the speech synthesis template relatively quickly, at least the first text which a reader is to read may be presented to the sender in a way in which certain words which have greater than a certain probability of being incorrect are emphasised and confirmation or correction of these words is prompted. Such confirmation or correction is incorporated into the learning process involved in generating the speech synthesis template so that it is able to be generated more effectively.  
     [0114] It should be understood that the speech synthesis templates do not necessarily need to be those belonging to users of the sending device  110 . All that is necessary is that they should distinguish between users when they are listened to. They can be chosen by the user of the recipient device  120  and may be “joke” speech synthesis templates, for example those to synthesise speech of cartoon characters. Alternatively there may be two speech synthesis templates, one for a male speaker and one for a female speaker. A gender indicator sent with a text message can ensure that the text message is spoken by a synthesised voice having the correct gender. One way of doing this is to check the forename of a user using the sending device and using this to determine the gender. Other discriminators could be used such as to have speech synthesis templates representing young and old voices.  
     [0115] As storage of a speaker&#39;s speech synthesis template could potentially enable fraudulent messages to be presented using someone else&#39;s “voice” it may be preferred to include some sort of digital signature in the speech synthesis templates (perhaps as an embedded signature) so that only the user who is the source of the speech synthesis template can use it legitimately. In one embodiment this is based on a two-key encryption system, in which the speech synthesis template generates one key and new text messages are provided with a second key. An encryption algorithm is used by the recipient device to check that the keys match with the content of the text message and thus to authenticate the source of the text message. These security aspects are not such a problem in methods, such as the fourth method, in which the speech synthesis templates are not transferred to communications devices.  
     [0116] If a text message comes from a number of people, a number of speech synthesis templates could be sent, so that different parts of the text message could be read out using different voices depending on the sources of the different parts of the text. In this case, source identifiers can be embedded in the beginning of a new source&#39;s portion in the text message. The case may apply to text messages which have been received by a number of recipients, all of whom have contributed some text, and then sent onwards. Such a text message may be an e-mail which has been received and forwarded or replied to one or more times.  
     [0117] The invention can be used on wired communication paths as well as on wireless ones, so that the invention can be used, for example, in cases where one or both parties are connected to an intranet or the Internet. In this case the sending device  110  and the recipient device  120  would not be mobile communications devices but would be fixed communications devices such as PCs (personal computers).  
     [0118] The speech synthesis templates of employees of an enterprise, for example all 1000 employees of a company, can be pre-programmed into the memories of communications devices used by the employees so as to avoid transmitting the speech synthesis templates unnecessarily. Equally, the speech synthesis templates may be stored in a company-run server from which they may be supplied to the communications devices.  
     [0119] The invention concerns a way of synthesising speech with the voice of a user. It also concerns a way of providing different synthesised voices for different users sending text messages. It is concerned with dealing with speech synthesis templates so that they can be made available for use by a communications device, either by transmitting them from one device to another or by transmitting them from a network to a device.  
     [0120] With the invention it becomes possible to send text messages which consume low bandwidth and have them spoken in a way to identify their sources. It provides a way of producing synthesised speech which is personal, or at least distinguishable between different sources. The invention enables such “spoken text messages” to be sent as simply as e-mail are sent at the moment. It also provides a way to enable provision of personalised speech synthesis templates whilst consuming low bandwidth in their transfer. This is especially the case in a method of the invention in which speech synthesis templates are only sent once. One advantage provided by the invention is that the text messages are still stored as plain text, which means that their storage uses little memory space compared to storing actual speech. Furthermore, it is relatively easy to search text messages with keywords.  
     [0121] Speech synthesis templates can also be put to other uses. In one embodiment, they are used to generate speech messages for answering machines, for example, a number of speech synthesis templates may be available which are able to synthesise the speech of people the sound of whose voices are generally known to the population. These people may be television personalities, actors, sportsmen, entertainers and the like. Such speech synthesis templates may be kept in a network-based library of speech synthesis templates. The speech synthesis templates are functionally connected to a suitable processor which is able to generate speech according to any speech synthesis templates which are selected. The library and the processor are conveniently co-located in a network based server. If a subscriber desires to have an answering message on his voice mail box, the subscriber sends a message to the server including text which is to form the basis of the answering message and indicating the voice in which the answering message is to be spoken and the voice mail box to which the answering message is to be applied. The processor uses an appropriate speech synthesis template to generate the synthesised answering message and the message is then transmitted to a memory associated with the voice mail box. When a call is made which leads to activation of the answering message of the voice mail box, the memory is accessed and the synthesised answering message is played to the caller. In another, refined embodiment, the operation is as in the foregoing but the subscriber sends the message not directly to the server but via his or her own telecommunications network operator. The operator can then authenticate and invoice the subscriber for the service thus removing the need for implementing any separate authentication and invoicing systems for collecting users (subscribers) of the service.  
     [0122] Particular implementations and embodiments of the invention have been described. It is clear to a person skilled in the art that the invention is not restricted to details of the embodiments presented above, but that it can be implemented in other embodiments using equivalent means without deviating from the characteristics of the invention. The scope of the invention is only restricted by the attached patent claims.