* The world's number 1 DAF app is used by thousands of people in over one hundred countries. *

DAF Professional has been created to help people who stammer or have a neurological disease such as Parkinson's Disease. It helps people to slow their rate of speech which makes it clearer to others.

DAF Professional is an easy to use professional speech therapy tool which could make a huge difference to you or someone you know.

DAF Professional has been designed and tested by a certified and practicing Speech and Language Therapist (MSc, PGDip, BAHons, HPC registered and member of RCSLT). DAF Professional delivers incredibly low latency feedback even when running in the background.

Delayed Auditory Feedback (DAF) is a well established speech and language therapy tool which helps people to speak more slowly. However, until recently, devices have been cumbersome to carry around, difficult to adjust, very expensive and therefore not widely used.

DAF was originally developed for people who stammer, but has since been shown to work with people with other speech difficulties, such as those with Parkinson's Disease (Downie et al., 1981; Dagenaise, Outhwood & Lee, 1998; Lowit et al., 2006 and most recentely Lowit et al., 2010).

It works by enabling someone to hear his or her own speech in an altered manner. This disruption to the normal auditory feedback loop causes the speaker to slow down. Research has shown that DAF will be of benefit to approximately a third of people who have a stammer or Parkinson's. Clinical research has not been carried out as yet on other client groups however DAF may well be of benefit to people with other medical speech conditions.

When using Bluetooth devices there is an additional delay of 60ms added to the feedback system.

If you do use a Bluetooth headset you may find you need to turn the bluetooth device on after opening the app to enable it.

DAF Professional works when put in the background or the screen is turned off. Like all apps of this type, it can NOT work during phone calls or with other media apps playing at the same time.

If you wish to provide any feedback we would be delighted to hear from you. Please email us at

Our lead Speech and Language Therapist is Samantha Brady who qualified as a Speech and Language Therapist in 2001 (PGDip, City University) and gained her Masters in Speech and Language Therapy in 2006 (MSc, City University). She has a wealth of experience of working as a Speech and Language Therapist in a variety of settings and her area of clinical expertise is adult neurology and voice. Samantha is a member of the Royal College of Speech and Language Therapists (RCSLT), HPC Registered (SL10250) and Lee Silverman Voice Treatment Certified (LSVT).

DAF Professional is fully GDPR compliant and will not collect any of your data without first asking for your consent.

What’s New

Version 3.2

Bug fixes and minor improvements

Ratings and Reviews

4.2 out of 5
18 Ratings

18 Ratings

Crackersmith ,

Thank you so much

From the bottom of my heart, thank you. I work in a call center and I have a stutter. I put an earbud in and put it on 55ms. I don’t stutter at all on the phone now. Then I forgot to put my earbuds in and I didn’t stutter. Hoping it will improve my speech overall after the repetition. It also helps me slow down my speaking and makes me feel calm. This app is priceless. Best 3 bucks I ever spent in my life. I feel hope that I will be able to speak fluently now. This has changed my life. Thank you and god bless

Developer Response ,

That's great to hear how useful it is for you, thanks for letting us know!

Charly Dat Duc Lai ,

I love this app so much!

Lord and the developer of this app, you have healed me. For a long time, I've stuttered/stammered but today when I tried out this app after purchasing and downloading it, an incredibly amazing miracle just happened. I was finally able to speak much more fluently with a tiny stammer or no stammers at all. Thank you so much for developing this app for those who need this.

Moone27 ,

Excellent DAF app

I have a speech disorder called cluttering, and this app has been a tremendous help. It is simple, yet very effective in helping me slow my rate of speech and improve articulation. And, the ability to record a sample and play it back for analyzing is a nice feature. Great app, highly recommended.

App Privacy

The developer, Speechtools Ltd, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy.

Data Not Linked to You

The following data may be collected but it is not linked to your identity:

  • Usage Data
  • Diagnostics

Privacy practices may vary, for example, based on the features you use or your age. Learn More


  • Family Sharing

    With Family Sharing set up, up to six family members can use this app.

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