Theory behind the VA601i system

What causes stuttering?

The exact cause of stuttering remains to be determined. Years of extensive research on stuttering only highlights that stuttering is a multi-factorial disorder and differs from individual to individual. Factors that contribute to stuttering include genetics, neurological factors, developmental factors and psychological factors to name but a few

The Choral Effect

It is well known that when people who stutter speak or sing in unison with others they become more fluent. This well documented phenomenon is known as the Choral Effect. The VA601i device uses digital signal processing technology to electronically reproduce the Choral Effect.

Altered Auditory Feedback

The VA601i uses a technique called Altered Auditory Feedback (AAF) to recreate the Choral Effect. The VA601i uses two forms of AAF, Delayed Auditory Feedback (DAF), and Masked Auditory Feedback (MAF) to enhance fluency.

The VA601i receives the user’s voice signal via a microphone. The voice signal is then processed by the device and altered using AAF techniques to produce a choral voice. The choral voice is then played back to the user via an earpiece.

The VoiceAmp Control Panel software allows the AAF settings to be customized for individual users.

Edinburgh Masking Function

This new tool (program 4) has recently been added to assist PWS with blocks or silent blocks; this program emulates the original Edinburgh Masking device (with some improvements). VoiceAmp has included additional calibration tools to the Control Panel software PC suite to allow users to tailor their preferences.

The Noise Gate

The VA601i system uses a microphone to capture the user’s voice and then electronically produces a choral voice using AAF techniques. In everyday situations there are various ambient sounds like other people speaking, traffic noise, large crowds etc. To prevent the unwanted sounds from being processed by the VA601i, a programmable Noise Gate was developed.


The above diagram illustrates the Noise Gate operation. Thesignal on the left contains both speech and noise sounds. Afterbeing processed by the noise gate, only the clean speechsounds remain.

The Noise Gate also reduces the amplitude or volume of veryloud sounds. This prevents unpredictable loud sounds such ashooters going off from being amplified.

This Noise Gate is fully programmable and parameters including attack, release and threshold can be adjusted using the ControlPanel software. For more information on the programmable Noise Gate, consult the Control Panel Reference Manual or HelpFile.

Contact and Support

VoiceAmp is continually improving existing technologies and exploring new techniques to improve fluency. We value your feedback. For technical support, please contact us.

Technical Support

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