Fono, Fono3 - Delayed auditory feedback (DAF) - stuttering treatment, speech pathology, for speech therapy clinics - speech therapists

Delayed Auditory Feedback

Delayed auditory feedback (DAF) can be used two, very different ways. The delay can be set between 50 and 70 milliseconds to reduce stuttering about 70% at a normal speaking rate, without training. DAF can also be used to support the fluency shaping target of slow speech with stretched vowels. For this purpose the delay is usually set at 200 milliseconds and then reduced to shorter delays (as short as 75 milliseconds) over the course of the therapy program.

For this latter purpose, a speech-language pathologist must train the stutterer. When the stutterer can complete a simple speaking task, such as counting to ten, using the slow speech target correctly, then he can use a DAF device. DAF therapy then has two goals:

1. To increase the length and complexity of the utterance, and increase the stress of the speaking situation, while using the DAF device to support on-target fluent speech.
2. To reduce the need for the DAF device, until the stutterer no longer needs the device.

For the first goal, after the stutterer can count to ten using the slow-speech target correctly (e.g., all syllables stretched equally, all syllables stretched to one or two seconds, no pauses between words, and no dysfluencies) without the DAF device, then use the device to have a conversation at the same slow speaking rate. When the stutterer can achieve the slow speech target with 100% fluency using the DAF device for utterances with the length and complexity of normal conversations, then the stutterer should take the device out of the speech clinic and use it in increasingly stressful conversations. The first goal is speech that is 100% fluent and on-target (i.e., slow) in any conversation. For a severe stutterer, this may mean using one- or two-seconds per syllables speech with the device set at 200 milliseconds.

When the stutterer achieves the first goal, then he gradually reduces his dependence on the device. He decreases the delay and increases his speaking rate. But if he has any dysfluencies he should go back to the longer delay and slower speaking rate. He can also decrease the volume, and use the device in one ear instead of both ears. He can use the device at the beginning of conversations, and then turn it off when he feels capable of speaking on target with the support of the device. He can discontinue using the device in low-stress conversations. Then he can discontinue using the device in medium-stress conversations, reserving the device only for stressful conversations such as public speaking. Eventually he should need the device only occasionally.

The common mistake with DAF is using a normal speaking rate with a long (slow) delay. If you want to talk at a normal speaking rate, set the DAF delay between 50 and 75 milliseconds.

Long-Term Effects. Nine adult stutterers used DAF devices thirty minutes per day, for three months. The thirty minutes consisted of ten minutes reading aloud, a ten-minute conversation with a family member, and a ten-minute telephone call. The devices were used with binaural (two ears) headsets. The subjects were allowed to set the delay where they wanted. Most selected delays around 100 milliseconds.

(Abbreviated from Wikibooks)