Delayed Auditory Feedback (DAF) Device Information
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. It can consist of a device that enables a user to speak into a microphone and then hear his or her voice in headphones a fraction of a second later.
DAF has been shown to induce fluency in many individuals who stutter, though not all stutterers experience enhanced fluency by this technique.
How Delayed Auditory Feedback Works
DAF can be used in two, very different ways.
- The delay can be between 50 and 70 milliseconds to reduce stuttering by 70% at a normal speaking rate, without training, mental effort, or abnormal-sounding speech.
- It 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.
A speech-language pathologist must train the stutterer in this second method. To begin, the stutterer is given a simple speaking task, such as speaking to ten using the slow speech method. After this is completed, the stutterer may then use a DAF device.
Goals of DAF Therapy
DAF therapy has two goals:
- 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.
- 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, the patient will then use the DAF 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 devices for normal conversations, the stutterer should then apply what they learned in the clinic to the outside world.
Using the device during stressful situations and achieving fluency and on target (slow) conversation is the goal. After the first goal is achieved, the stutterer will start to gradually reduce dependence on the device. Decreasing the delay and increasing the speaking rate. If there are any dysfluencies that persist, the stutterer should go back to longer delay and slower speaking rate.
Lowering the volume and using the device in one ear instead of both can also be a way to slowly rely less on the DAF.
The Role of Speech-Language Pathologists (SLPs)
You are not alone! Speech-language pathologists evaluate and treat individuals who stutter. A few fluency strategies taught in fluency therapy are slow/easy speech, easy onsets, deep breathing, and strategic pausing. SLPs may also use auditory (hearing) feedback tools to improve a person’s fluency.
Delayed auditory feedback (DAF) is a device used where the patient puts on headphones and the tool delays the sound of their voice by milliseconds. Delayed auditory feedback is reported to stimulate the area in our brains responsible for processing sound information. DAF can help increase the individual’s awareness of their stutter and improve their self-monitoring skills. They can enhance their fluency by applying techniques learned in speech therapy. Practice using DAF in high-stress talking situations to meaningfully practice the implementation/use of the device.
Additionally, DAF was found to reduce overactivity in the speech motor control area of the brain and decrease extraneous muscle movement when speaking.
Altered Auditory Feedback (AAF) Features
The SmallTalk provides two types of altered auditory feedback (AAF):
- Delayed auditory feedback (DAF) immediately reduces stuttering about 70% at normal speaking rates without training, mental effort, or abnormal-sounding or abnormally slow speech; and trains 55% carryover fluency (after removing the device), without speech therapy. With speech therapy, DAF can induce a slower speaking rate with stretched vowels to make even severe stutterers nearly 100% fluent.
- Pitch-shifting frequency-altered auditory feedback (FAF) immediately reduces stuttering about 70% at normal speaking rates and induces speech motor changes in stutterers.
Combining DAF and FAF increases effectiveness.
DAF Online Tool
Delayed Auditory Feedback (DAF) is a scientifically backed method used in speech therapy that plays a speaker’s voice back with a short delay. Our DAF Online Tool lets you experience this technique instantly in your browser, with no downloads or installations required. When you speak, your brain expects to hear your voice immediately. DAF introduces a delay (e.g., 20-200 milliseconds), which disrupts the feedback loop and causes the speaker to unconsciously slow down or modify their speech pattern.
Using the Delayed Auditory Feedback (DAF) tool is simple:
- Adjust the delay time: Move the delay slider to adjust the feedback delay.
- Practice speaking: Once activated, speak into the microphone.
This tool uses your browser’s microphone to capture your voice, then plays it back with a customizable delay. No installation is needed. Yes! Give it a go!
Important: Avoid Bluetooth headphones - they add extra delay that disrupts DAF effectiveness.
| Goal | Method | Description |
|---|---|---|
| Increase utterance length and complexity | Use DAF device during conversations | Support fluent speech in stressful situations |
| Reduce dependence on DAF device | Decrease delay and increase speaking rate | Gradually rely less on the device |