Delayed Auditory Feedback (DAF), also called delayed sidetone, is a type of altered auditory feedback that consists of extending the time between speech and auditory perception.[1] It can consist of a device that enables a user to speak into a microphone and then hear their voice in headphones a fraction of a second later. Some DAF devices are hardware; DAF computer software is also available. Most delays that produce a noticeable effect are between 50–200 milliseconds (ms). DAF usage (with a 175 ms delay) has been shown to induce mental stress.[2]
It is a type of altered auditory feedback that—along with frequency-altered feedback and white noise masking—is used to treat stuttering; it has also demonstrated interesting discoveries about the auditory feedback system when used with non-stuttering individuals. It is most effective when used in both ears. Delayed auditory feedback devices are used in speech perception experiments in order to demonstrate the importance of auditory feedback in speech perception as well as in speech production.[3]
There are now also different mobile apps available that use DAF in phone calls.