35.4 INTERACTIVE VOICE RESPONSE SYSTEMS

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35.4 INTERACTIVE VOICE RESPONSE SYSTEMS

The interactive voice response (IVR) system is a simple yet efficient system for retrieving the information from computers in speech form through telephones. As shown in Figure 35.3, the IVR hardware consists of a PC add-on card. This card has a telephone interface to connect to the telephone in parallel. Any telephone subscriber can call the IVR number (the number of the telephone to which the IVR card is connected) through the PSTN to access the information available on the computer in which the add-on card is located.

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In an interactive voice response (IVR) system, a PC add-on card has telephone interface circuitry. A subscriber can call an IVR system and access the information stored in the PC. The information is converted into speech form and sent to the subscriber.

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We will study the functioning of an IVR system, its architecture, applications, and design issues in this section.

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Figure 35.3: Interactive voice response system.

35.4.1 How an IVR System Works

Consider the example of obtaining train reservation status information through an IVR system. You hold a ticket for a particular train—the ticket contains the ticket number, the train number, and the reservation status when you purchased the ticket. The IVR system of the railway authorities contains the complete database with the latest information on the reservation status. To find out the status of the reservation at any time, you can call up the IVR system. You dial the IVR number and hear a response: "Welcome to the IVR system for reservation status enquiry. Please dial the train number". You dial the train number by pressing the digits on the keypad. The IVR system will prompt again: "Please dial your ticket number". You dial the digits 765391. The system will open the database corresponding to the reservation for the given train and check the status for the given ticket number. The database contains three fields: confirmed, S7, and 64, indicating that the ticket has a confirmed berth in coach number S7 and berth number 64. The system will convert this information into a sentence: “Your ticket is confirmed, coach number is S7, and berth number is 64. Note that coach number and berth number are obtained from the database and put at the appropriate places in the sentence; these fields will vary for different users. The next step is to convert this sentence to speech form. Speech data corresponding to all these words is stored in the computer along with data corresponding to all digits. This data is concatenated (joined together) to form the sentence, and the data is converted into analog form and sent over the telephone line.

We can now see the great advantage of an IVR system—the data available on computers can be retrieved without the need for a computer at the user's end, just through telephones. There is no need for an operator for providing reservation status—our IVR system is user friendly, does not take coffee breaks, and above all, gives polite replies. It is not surprising, that IVR systems have gained wide acceptance all over the world.

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In an IVR system, the user is presented a menu of items. The user can select a menu item by pressing the corresponding DTMF digit on the telephone keypad. The information corresponding to that menu item will be sent to the user.

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We can now see that the IVR system should have the following functional blocks for the hardware:

  • Telephone interface circuitry, to pick up a call and to recognize the various tones (the user may put back the telephone after dialing a few digits, and the circuitry has to take care of such situations).

  • PC interface circuitry to interact with the PC and obtain the data (the speech files).

  • Circuitry to recognize the digits dialed by the user. Two types of dialing are possible: pulse dialing in which each digit is represented by a set of pulses and DTMF signals in which each digit is a combination of two sine waves.

  • A PCM codec that converts the digital speech stored in the computer to analog form to transmit on the telephone line.

  • Control circuitry to control all functional blocks.

In addition, the IVR system contains the software that takes the recognized digits from the hardware, accesses the database, generates the required response, converts the response into speech form by concatenation of different speech data files, and passes the speech data to the IVR hardware. Before getting into the architecture, let us see the various applications of IVR.

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An IVR system consists of telephone interface circuitry, PC interface circuitry, circuitry to recognize the digits dialed by the user, a PCM codec, and control circuitry, in addition to the software to generate the desired responses.

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IVR Application Panorama

IVR systems find use in almost every business sector. Some representative applications are as follows:

Automated attendant: Information required by clients/customers can be provided even after office hours and during holidays.

Telemarketing: Marketing agencies can provide the information required by customers (such as prices of items, stock availability, features of items) automatically to their customers.

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IVR systems have applications in a number of areas such as telemarketing, telebanking, telesurveys, value-added service provisioning by service industries, entertainment, and fax-on-demand.

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Teleshopping: Customers can dial into the IVR system and place an order for the required item (by dialing the required item number, quantity, and so on). If payment is by credit card, the credit card number also can be input by the customer.

Banking: Banks can provide services whereby a customer can dial into the IVR system to find out the bank balance, currency exchange rates, information about the various deposit schemes, and so forth.

Talking Business Directory: An IVR system can contain category-wise information about various products. The user will be provided with a voice menu from which he can select the required product and hear a beautiful voice explaining the salient features of the product. These talking business directories will be user friendly and can be updated frequently.

Telesurveys: Marketing agencies, government organizations, broadcast agencies, and such can conduct surveys through IVR systems. Users will be asked to dial a specific number (telephone number of the IVR system) and then dial various codes to convey their opinions, which will be recorded and stored for subsequent processing.

Value-added services by telecom operators: Telecom operators can provide services such as morning alarm service, changed number announcement service, telephone bill reminder service, fault booking service, bill enquiry service, and so on using an IVR system without any human intervention.

Transport agencies: Airlines/railways/bus transport authorities can use an IVR system for automatic announcement of arrivals/departures, reservation status enquiry, cargo status enquiry, and others.

Entertainment: One popular IVR application is to obtain astrological predictions—the user has to dial his date and time of birth, and the IVR system will give the astrological predictions for the year or the month or the day. Another popular application is audio-on-demand—one can dial an IVR system and listen to a music recital, a Shakespearean drama, or a novel by Pearl S. Buck. To use an old cliché, for IVR in entertainment, imagination is the limit.

Fax-on-demand: One can dial an IVR system and listen to a menu that gives details of fax messages that can be received by a user (for example, product literature). The user can select an item and then input the fax number to which the fax message has to be sent. The selected message will be faxed to the user. Of course, an additional module that invokes fax transmitting software (such as Microsoft Fax, BitWare fax, or WinFax pro) is also required along with an IVR system.

Every market segment—government, corporate, health care, transport, telecommunication, education, entertainment, banking, social service organizations—can apply IVR technology to increase productivity and to reduce human resources for carrying out mundane activities. That is the reason IVR is a multibillion dollar industry in both developed and developing countries.

35.4.2 IVR System Architecture

As shown in Figure 35.3, the IVR system consists of IVR hardware (generally a PC add-on card), a PC, and application software running on the PC. The IVR hardware is connected in parallel to the telephone line. The requirements of the IVR hardware are:

  • To go off-hook (automatic lifting of telephone) when a user calls.

  • To recognize the digits dialed by the user.

  • To interact with the PC to obtain the necessary speech files and also to send the recognized digits to the PC for further processing.

  • To convert the digital speech into analog form and send it to the telephone line.

  • To convert the analog speech from the telephone line (if recording of incoming speech is required) into digital form and send it to the PC for storage.

The entire circuitry corresponding to these requirements is generally in the form of a PC add-on card that sits on the motherboard of the PC.

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The functionality of the IVR hardware is to lift the telephone automatically when the user calls, recognize the digits dialed by the user, interact with the PC to obtain the necessary information, convert the information into speech form and convert the incoming speech into digital form and store it in the PC.

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This circuitry is for a one port IVR system because the IVR system has one telephone line interface. If the application demands multiple ports (such as 2, 4, 8), additional circuitry is required to handle that many ports. Applications such as a railway status enquiry require multiple ports because many users will access the IVR system simultaneously.

Note 

To reduce the storage requirement, instead of using PCM, low-bit rate coding techniques such as ADPCM LPC can be used to store the speech waveforms.

35.4.3 IVR Application Design Issues

In designing an IVR system, the human factors are the most important—after all, the user has only a telephone keypad for interaction with the computer. Designing a cost-effective and user-friendly IVR system involves the following issues:

  • Selection of application: The application should not be too general or too narrow. If it is very general, the user has to be presented with a long menu that will be difficult to remember. Too narrow an application will not make the best use of the IVR system's capabilities and will not be cost effective.

  • Design of user interface: The menu to be presented to the user should have typically four or five choices. For each choice, there can be a submenu. Provision should be made to go back to the previous menu item.

  • Design of database: The database can be a short text file or it can be a popular RDBMS package. From the user's dialed responses, the information has to be accessed by generating the appropriate query to the database.

  • Text-to-speech conversion: If the response to the query is of limited vocabulary, speech corresponding to the words can be stored directly. If the vocabulary is large (or unlimited), text-to-speech conversion software needs to be used. It is important to ensure that proper names are pronounced correctly.

  • Number of ports: The traffic that has to be handled by the IVR system decides the number of ports. Based on the number of simultaneous calls that have to be handled by the IVR system, the number of IVR ports can be anywhere between 1 and 64. The system can also be upgraded as the traffic goes up.

  • Pulse-to-tone conversion: A good number of telephone users still use rotary (pulse) telephones, whereas most of the commercially available IVR systems are based on DTMF (tone) detection. A pulse-to-tone converter may be necessary if access is to be provided to all the telephone subscribers without restricting access to only those who have DTMF telephones.

  • Accuracy of digit recognition: Accuracy of recognition of the DTMF digits dialed by the user is extremely important for an IVR system to respond correctly. Most of the DTMF recognition chips achieve an accuracy up to 99%, which is sufficient for most applications, but not for applications such as banking and credit card verification. In such sensitive applications, the IVR system can speak the dialed digits and ask for confirmation by the user (for example, the user can dial one to confirm, zero to indicate that the digits recognized are not correct).

    Nowdays, more sophisticated IVR systems are becoming available wherein voice recognition is employed. The user need not dial the digits; instead, he can speak the digits. Even for such systems, the above issues need to be considered in designing a user-friendly IVR system.

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The various issues to be considered while designing practical IVR systems are selection of a focused application, user interface design, database design, text-to-speech conversion algorithm, number of ports, need for pulse-to-tone conversion, and the accuracy of digits recognition.

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Principles of Digital Communication Systems and Computer Networks
Principles Digital Communication System & Computer Networks (Charles River Media Computer Engineering)
ISBN: 1584503297
EAN: 2147483647
Year: 2003
Pages: 313
Authors: K V Prasad

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