Delayed Auditory Feedback

Delayed Auditory Feedback

Auditory Feedback (DAF), also known as Delayed Side-Tone is an altered auditory
feedback which involves time extension between speech & audio perception.
It may consist of a device which enables a person to speak on a microphone and
then be able to hear their voice in headphones a few seconds later. A DAF
device can either be hardware or computer software. Currently, there are many different
mobile applications available that use the delayed side-tone effect in phone

This type of
altered audio feedback when combined with white noise masking and frequency
altered feedback is used to treat a condition known as stuttering. The delayed
effect has also shown interesting discoveries when used with non-stuttering people.
Its effectiveness is best experienced when used in both ears.

DAF Effects in Stuttering Individuals

Fluency devices which feature delayed auditory feedback use it to aid with
stuttering. This is because studies have shown that individuals who stutter
have abnormal speech and auditory feedback loop which can be bypassed or
corrected if they are put under DAF. For stutters with a normal auditory
anatomy, altered auditory feedback will improve their fluency.

DAF Effects in Normal Individuals

There have
been studies on non-stuttering individuals to find out the effects of DAF and
what it can prove about verbal and auditory pathways in brain. The results have
shown than the effects include increased fundamental frequency, increased
speech intensity and reduced speech rate. Other noticeable and direct effects
include mispronunciations, word omissions and repetition of syllables. The
results also show that more men are affected than women which might indicate that
the feedback systems in both genders could be different.

fluent and rapid speakers are less affected by DAF when compared to slower &
less fluent speakers. Also most delays which produce noticeable effects are
between 50 to 200 milliseconds. Note that a DAF delay of 175 milliseconds can
induce mental stress.


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