# DAF Pro

> Delayed auditory feedback for fluency

DAF Pro plays your own voice back to you after a short, adjustable delay – a technique called delayed auditory feedback. Many people who stammer or have Parkinson’s find that it helps them to slow down and speak more steadily.

Yes. A smartphone can replace a dedicated DAF device for many users. DAF Pro provides low-latency feedback, meaning very little unwanted lag is added to the delay you set.

## Facts

- Platforms: iPhone, iPad, Android
- Pricing: One-off purchase. Not a subscription.
- App Store: https://apps.apple.com/app/id491299921?pt=102524862&ct=web-markdown&mt=8
- Google Play: https://play.google.com/store/apps/details?id=co.speechtools.DAFPro&referrer=utm_source%3Dspeechtools.co%26utm_medium%3Dwebsite%26utm_campaign%3D%2Fdaf-pro.md
- Rating: 4.06 from 16 ratings (GB App Store, fetched 2026-08-18)
- Page: https://speechtools.co/daf-pro
- Reviewed: 2026-08-19

## Was it designed by a speech and language therapist?

Designed and tested by a specialist speech and language therapist, and the app that started Speechtools — built in 2011 because the clinic hardware was expensive and hard to borrow. It is listed in the [Parkinson’s UK Tech Guide](https://techguide.parkinsons.org.uk/catalogue/daf-pro) and among the [apps and devices STAMMA lists](https://stamma.org/get-help/people-who-stammer/therapy-courses-self-help/apps-fluency-devices) for people who stammer.

## What can you do with it?

- **Four controls, one screen** — Users can adjust the delay, pitch change, microphone boost and background mute in one place, making DAF Pro simple and easy to use.

## Who can DAF help?

DAF is a fluency technique rather than a treatment, and it suits some people and not others — which is why it’s so useful to try on your phone and quickly find out whether it helps, without the need to buy a separate DAF device.

- **People who stammer** — Use DAF as a fluency aid throughout the day or just in specific speaking situations when you need extra support
- **Parkinson's and neurological conditions** — Where speech has become fast or unclear
- **Speech and language therapists** — Use DAF as part of assessment or therapy directly from a phone, without the need for dedicated hardware

## How is DAF used for stammering and Parkinson’s?

- [Delayed auditory feedback for stuttering](https://speechtools.co/guides/delayed-auditory-feedback-for-stuttering.md) — What delayed auditory feedback is, who it helps, and how to try it on a phone rather than with dedicated hardware.
- [Parkinson's voice exercises at home](https://speechtools.co/guides/parkinsons-voice-exercises-at-home.md) — Why Parkinson's affects the voice, what daily practice looks like, and how to keep it going between appointments.

## Common questions

### What is delayed auditory feedback?

It plays your voice back to you through headphones a fraction of a second after you speak. Many people find that hearing their voice back with a delay slows their speech and makes it steadier.

### Do I need headphones?

Yes. The delayed sound has to reach your ears without the microphone picking it up again. Wired or Bluetooth both work.

### Do I need to use wired headphones for DAF?

Wired headphones generally give the best performance, but many users try both wired and wireless options to find what works best for them in different situations.

### Does it keep working with the screen off?

Yes. DAF Pro carries on running with the device locked, so you can put the phone in a pocket during a conversation and it will not drain the battery keeping a screen lit.

### Can I hear how I sounded?

Yes. You can record yourself while the delay is running and play it back, which is how most people work out which delay setting suits them.

### Is there a subscription?

No. DAF Pro is a one-off purchase — you buy it once and there is nothing further to pay.

### How much does it cost?

The current price is shown on the App Store and Google Play, in your own currency. Follow either badge on this page to see it.

### Is the app available in my language?

DAF Pro is in 25 languages: Arabic, Danish, Dutch, English, French, German, Greek, Hebrew, Hindi, Indonesian, Italian, Japanese, Korean, Malay, Norwegian Bokmål, Polish, Portuguese, Russian, Simplified Chinese, Spanish, Swedish, Thai, Traditional Chinese, Turkish and Vietnamese. Delayed auditory feedback works the same whatever language you speak.