[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.
The above is consistent with behavioral studies that demonstrate that stutterers present reduced compensatory motor responses to unexpected perturbations of auditory feedback.
[6] The mechanism of action of DAF is to reduce the speed of speech in such a way that the longer the delay time, the greater the reduction is made.
Furthermore, DAF is believed to continue to cause increased fluency over a long period of time, but reports of long-term effects are inconsistent.
[5] Studies that are more recent have looked at the effects of DAF in people who do not stutter to see what it can prove about the structure of the auditory and verbal pathways in the brain.
[9] Delayed auditory feedback can be constructed using a speaker pointed at the person speaking, yielding a "speechjammer".
As the data collected from these studies indicate, the delay required for maximum disruption decreases with age.
Studies using computational modeling and functional magnetic resonance imaging (fMRI) have shown that the temporo-parietal regions function as a conscious self-monitoring system to support an automatic speech production system[16] and that projections from auditory error cells in the posterior superior temporal cortex that go to motor correction cells in right frontal cortex mediate auditory feedback control of speech.
[19] Moreover, in experiments, DAF is used to selectively interrupt auditory feedback in such a way that when adult zebra finches are exposed, their songs degrade and when discontinued they recover.