 Some DAF devices are hardware; DAF computer software is also available.Most delays that produce a noticeable effect are between 50-200 ms. DAF usage (with a 175 millisecond delay) has been shown to induce mental stress.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.