Evidence-based tool for stuttering therapy and fluency improvement
EchX DAF uses scientifically-proven Delayed Audio Feedback technology to help reduce stuttering and improve speech fluency. Completely free, no registration required.
Learn more about DAF, stuttering, and speech fluency with our in-depth articles.
A teenager from Poland, a borrowed DAF device, one summer of practice, and the first day that changed everything.
Read my story → Nov 18, 2025When to seek help, how to support your child, and age-appropriate ways to use DAF therapy.
Read the guide → Dec 7, 2025Structured practice routines from beginner to advanced with reading passages and conversation scripts.
Get the exercises → Sep 22, 2025A casual guide to understanding DAF technology, how it actually works, and why it's not as weird as it sounds.
Check it out → Oct 29, 2025My top tips and tricks for getting the best results out of Delayed Auditory Feedback therapy.
Learn the tricks → Jan 8, 2026A breakdown of the research and evidence that proves DAF is actually a legit tool for fluency.
See the science →Okay so here's the deal - DAF is basically this thing where you hear your own voice with a tiny delay, and somehow that makes you speak more smoothly. Sounds weird right? But it actually works, and theres like 50+ years of research backing it up.
So when you talk, your brain is constantly listening to itself. It's like a feedback loop - you say something, your ears pick it up, your brain checks if everything's going according to plan, and then keeps going. This whole thing happens in milliseconds and you don't even think about it.
But for people who stutter, this feedback loop gets kinda... janky. The timing's off, signals get crossed, and thats when you get blocks and repetitions. It's not a confidence thing or a mental thing - its genuinely neurological. Your brain's internal metronome is just doing its own thing.
Here's where DAF comes in. When you hear your voice with a delay (usually around 50-200 milliseconds), your brain goes "wait what?" and kind of... resets. It creates something researchers call the "choral effect" - basically your brain thinks someone else is talking with you in unison. Same reason why most people who stutter can sing perfectly fine, or why reading out loud together with someone else feels easier.
The delayed feedback essentially tricks your brain into using a different neural pathway for speech. Instead of the one that's been giving you trouble, you start using the pathway that handles music and synchronized speech. And that pathway? Usually works pretty darn well.
DAF wasn't invented recently - people have been messing with this since the 1950s. A guy named Bernard Lee discovered that when you play someone's voice back to them with a delay, even people who DON'T stutter start tripping over their words. This got called the "Lee Effect."
But then researchers noticed something weird: for people who DO stutter, the opposite happens. The delay actually made them more fluent. Go figure. Since then, thousands of studies have been done, and DAF is now recognized as a legit tool by speech pathologists worldwide.
Honestly? Lots of people. But to give you some specifics:
Look, I gotta be straight with you. DAF isn't magic. It won't "cure" stuttering overnight, and it's not a replacement for working with a speech-language pathologist if you have access to one. Think of it more like a really useful tool in your toolkit - one that's backed by actual science and doesn't cost you anything to try.
Also worth noting: the effect can vary a lot person to person. Some people put on headphones and immediately speak way more fluently. Others need a few sessions to find their sweet spot. And some people (roughly 20-30%) don't respond to DAF much at all. That's just how it is - brains are weird and complicated.
Our app processes your voice in real-time with ultra-low latency to provide effective DAF therapy.
Use your device's built-in microphone or connect an external mic. The app captures your voice in real-time.
Choose your delay between 50-200ms. Most users find their optimal setting through experimentation, typically 75-150ms.
Hear your delayed voice through closed-back headphones or earbuds. Your brain adapts and speech becomes more fluent.
20-30 minutes of daily practice produces the best results. Consistency is more important than session length.
All audio processing happens locally on your device. No audio is ever transmitted to external servers. Your privacy is fully protected.
Alright, you want the science stuff? Fair enough. DAF isn't just some random thing I made up - it's been studied extensively since the 1950s. Here's what the actual research says:
Bernard Lee published his findings in 1950 showing that delayed auditory feedback disrupts speech in non-stuttering individuals - what became known as the "Lee Effect." Later research by Goldiamond, Chase, and others in the 1960s showed the opposite effect in people who stutter.
Lee, B.S. (1950). "Effects of Delayed Speech Feedback." Journal of the Acoustical Society of America, 22(6).
Meta-analyses generally show that DAF produces stuttering reductions of around 40-80% in responsive individuals. One notable study by Stuart et al. (2004) found that altered auditory feedback (DAF + FAF) reduced stuttering by an average of 70% in their subjects. Thats pretty significant if you ask me.
Stuart, A., Kalinowski, J., Rastatter, M.P., et al. (2004). "Effect of altered auditory feedback on stuttering frequency." PMID: 15285473
fMRI studies have shown that DAF increases activity in the right hemisphere speech regions - areas that are typically less active in people who stutter. Basically, DAF seems to activate backup speech pathways that work more reliably.
Watkins, K.E., Smith, S.M., Davis, S., & Howell, P. (2008). "Structural and functional abnormalities of the motor system in developmental stuttering." Brain, 131(1). DOI: 10.1093/brain/awm241
Some research suggests that regular DAF use can produce lasting improvements even when the device isn't being used. This appears to be related to neuroplasticity - your brain literally rewiring itself through repeated practice. Not everyone sees this, but a good chunk of long-term users report it.
Kalinowski, J., & Stuart, A. (1996). "Stuttering amelioration at various auditory feedback delays." European Journal of Disorders of Communication, 31(3).
If you're the type who actually reads research papers (respect), here are some good starting points:
Got questions? Yeah, I figured. Here are the ones I get asked the most:
Start with 100ms - that's the sweet spot for most people. Then mess around with it. Go up to 150ms, down to 75ms, see what feels right. Everyone's brain is wired a little differently so there's no magic universal number. Some people do better with shorter delays, others prefer longer ones. You'll know when you hit yours because speaking will suddenly feel... easier. Like the words just flow better.
Here's the weird thing - most people notice something immediately. Like, within the first minute of trying it. Whether that's a big improvement or a small one varies, but something usually clicks right away. For lasting changes though? You'll want to practice regularly for at least 2-4 weeks. Think of it like working out - one session feels good, but you need consistency for real results.
Okay so this gets into neuroscience territory but I'll try to keep it simple. When you talk, your brain is constantly monitoring your own voice to make sure everything's on track. For people who stutter, this feedback loop gets messy - timing is off, signals get crossed. The delay basically "resets" this loop and tricks your brain into using a different speech pathway. Same thing that happens when you sing or read in unison with someone else. Your brain thinks someone else is talking with you and switches to a smoother mode.
Honestly? No. DAF is a tool, not a complete solution. It's best used alongside actual speech therapy, not instead of it. A good speech-language pathologist can help you with stuff that DAF can't - like identifying triggers, working on secondary behaviors, building confidence, all that. Think of DAF as one really useful tool in your toolkit, not the whole toolkit.
Good news - DAF is pretty much the definition of non-invasive. No weird chemicals, no procedures, just audio through headphones. The only thing to watch out for is keeping the volume reasonable - don't blast it. Some people find the delayed voice thing a bit trippy at first (its honestly kind of weird the first time you try it) but you adapt pretty quick. Maybe 30 seconds to a minute and it starts feeling normal.
Yep, but with supervision - especially for younger kids. I'd really recommend having a speech-language pathologist involved if you're using this with a child. They can help set things up correctly and make sure it's being used effectively. For teens, it's generally fine to use more independently, just like any other audio-based tool.
No catch, I promise. I made this because DAF genuinely helped me with my own speech, and professional DAF devices are stupidly expensive (like hundreds of dollars). I figured that's not fair - if the technology works, everyone should have access to it regardless of their financial situation. The app has some ads to keep the lights on, but that's it. No premium version, no hidden paywalls, no "pay to unlock the features that actually work" nonsense.
Nope. All audio processing happens right on your device. Nothing gets sent to any server. I'm not interested in your voice recordings and honestly the app doesn't even have the capability to upload them anywhere. Your privacy is completely protected.
Honestly, no. About 20-30% of people who try DAF don't respond much to it. Brains are weird and complicated, and what works great for one person might not do much for another. But since it's free and takes about 5 minutes to try, there's really no downside to seeing if it works for you. And if you're in the 70-80% who do respond, it can be pretty life-changing.
Technically yes, but there's a catch - you need to be wearing headphones anyway and have the app running in the background. The web version might interfere with some video call apps (they fight over the microphone sometimes). The Android app tends to work more reliably in this scenario. Some people use DAF regularly for work calls and say it's been a game changer for presentations and meetings.
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Have questions, feedback, or feature requests? I'd love to hear from you.
Email: this.is.michal.nawrot@gmail.com
Note: EchX DAF is not a medical device. For clinical concerns about stuttering, please consult a qualified speech-language pathologist.