Extending the portfolio of speech processing
technologies that can work alongside Prosody, a biometric SVI option is available. SVI provides the most cost effective, convenient and secure way to access personal information over the telephone. It enables applications to be developed to provide access to sensitive data or enhances existing access to secure areas.

I am, I said
The biometric technology captures the physical characteristics of the human voice to verify individuals are ‘who they say they are’ using just a single utterance over the telephone or a network connection.

Aculab SVI uses statistical information to confirm a caller’s identity based on the characteristics of his or her unique voiceprint.

The availability of this host based SVI module brings yet more choice to developers using Prosody media processing resources. Available under a cost free licence, this confirms Aculab’s commitment to offer unmatched value and features for speech processing.

The use of Aculab SVI can enhance a range of applications. For example, it can provide secure access to a company’s Intranet/extranet or corporate applications and reduce costs associated with resetting PIN numbers.

Contact centre applications using SVI can reduce the workload of operators and agents where previously verification of identity or password resets required manual intervention. Agents can then concentrate on other revenue generating activities.

SVI applications can be targeted at the telecoms sector for calling card, cellular roaming, unified messaging and auto-attendant systems to reduce fraud, protect personal information and gain competitive advantage.

Within the travel industry, SVI systems can be provided for frequent-customer service interactions, promoting convenience and personalisation.

Use with Aculab automatic speech recognition (ASR)
Simultaneous speech recognition and speaker verification allows applications to verify the caller based on their voice and on a piece of personal knowledge, for an even more secure verification. SVI based applications can automatically detect callers whose voiceprints are difficult to correctly authenticate and request additional information from them.

SVI is delivered as part of Aculab’s ASR and this allows SVI and speech recognition to run simultaneously. Integration with the same server software also minimises latency and reduces call duration. It has been integrated seamlessly into the existing generic API.

Scalable architecture
With Prosody S or high density Prosody cards providing multiple channel feeds, verification channel capacity is only limited by the processing power of the ASR/SVI server. Using additional servers will expand the channel capacity. Flexibility is built into the architecture, allowing single or multiple distributed servers to fully exploit the capabilities of the Prosody media processing resources.

Used in isolation, Aculab SVI is language independent. If used in conjunction with ASR, it will support British and American English, North American Spanish, French, Italian, and German. Each language is available on a per verification basis, although they may not be used simultaneously for a single recognition.


Prosody options
Aculab SVI is used with Prosody cards in PCI or cPCI formats that provide an audio feed via an E1 or T1 network line interface. It can also be used with Prosody S as the SVI software is compatible with any media processing firmware that supports 64kbits/s record. This allows ASR and SVI to be run in parallel with other media processing resources, such as playback, echo cancellation and DTMF detection, providing a versatile mixture of speech technologies on the same platform.

The frequency with which target speakers are rejected and the frequency with which impostors are accepted are factors used to determine the performance of a verification system. The system performance is improved by reducing both values. It is possible to set a threshold where the percentage of false rejections and false acceptances are of the same value; this is called the ‘equal error rate’ (EER).

Aculab SVI has achieved a 4% EER. This was achieved using single utterance testing. A lower EER may be achieved if the application uses pass phrases.

In terms of channel count, using a 1.9GHz P4 CPU with 400MHz bus and 1Gb of RAM, SVI can verify 120 concurrent callers.


  • Speaker enrolment and deletion enables a new speaker to be added to the system by providing some training data and a unique user name. Additional data, plus a PIN or password for added security and further training data, can be requested.

  • Speaker verification allows a speaker to make an identity claim and the system accepts or rejects that claim.

  • Speaker identification will return the details of the speaker that best matches the incoming speech.

  • Speaker adaptation can be used every time a speaker passes a subsequent verification test; their template can be updated using the latest examples of their speech.

  • High verification accuracy is achieved using only a few seconds of speech.

  • Continuous monitoring can be used to monitor a speaker's voice throughout a call. For example, if run concurrently with ASR to recognise a password and verify the speaker, this enables a more secure service provision.

  • Scalable architecture is possible where a distributed server allows the system to be easily expanded.

  • Aculab’s generic API ensures ease of integration and faster time to market.

  • A cost free licence enables SVI software to be downloaded from software downloads, when and where you need it, with no per channel costs or recurring licence fees.

  • Grunt detection is used to identify the endpoints of the utterance and minimise system loading. Parameters can be adjusted via the API.

  • Echo cancellation can be performed simultaneously on the Prosody media processing resource card(s) to prevent spoken passwords being echoed and leading to a false rejection.


  • Leverage existing infrastructure with SVI using any ordinary telephone without the need for additional equipment such as scanners or cameras.

  • Limit agent interventions by eliminating the need for manual password resets. The system frees valuable agent time and can pay for itself in a matter of months.

  • Reduce fraud while providing an effective means for secure voice-enabled commerce. Cellular access and credit card information are just two areas that can be protected with voiceprints for improved security and consumer convenience.

  • Caller convenience can be increased when used in conjunction with ASR and other recognisers i.e., the caller can be recognised and verified as an account number is spoken, reducing the requirement to remember and enter a password.

  • Enhanced security is gained when combined with a password; an SVI system adds another level of security, confirming the correct individual said the correct password.


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