This android application implements Delayed Auditory Feedback (DAF) technique, which is known to help people with stuttering to speak more fluently. The application works by recording the speech through your headset, applying this technique and playing the delayed audio back to you. Frequency Altered Feedback (FAF) is not currently supported, but it will be soon.
I used to be more fluent in loud environments where I couldn't hear myself, including when listening to music on headphones (where I can't hear myself but others can hear me). I don't think, however, there is more to it than just providing a distraction. I think it's just that when you hear yourself differently, it breaks off the feedback loop and tricks your brain into thinking you're speaking fluent.
You can't have a conversation with a really loud music in the headphones, but it not the only method of tricking the brain!
I've red some papers on the matter. Studies shows that stutterers commonly report dramatically increased fluency when singing, whispering or starting speech from a whisper, speaking extremely slowly, speaking in chorus, speaking without hearing their own voice (e.g., speaking over loud music), speaking with a metronome or other rhythm, speaking with an artificial accent or voice, speaking in a foreign dialect, or when speaking while hearing their own voice with a minuscule delay or pitch change.
So, instead of listening to loud music, we can listen to ourselves (and others) with a slight delay, effectively breaking stuttering patterns.
This application uses DAF to aid stuttering. I myself use this application and it does wonders to my speech. It's not that I'm cured or something. Furthermore, after several days of using this application brain gets used to altered feedback and tries to ignore it (I think it is important to force brain to focus on delayed feedback). But I think that it is a great tool to help your brain to get new habits and reflexes, allowing you to speak calmly and breathe properly.
The application can operate in the background. Android OS supports multitasking, the application will continue to run in the background while you are checking your SMS, browsing the web or doing something else (except calling or listening to music, of course). It even continues to run if you switch off the phone screen using power button! Which allows to conserve power, I'm getting about 8-10 hours run on my Samsung Galaxy S.
You can control the application using the headset button. You can still receive calls, but when you're not on call you can start or stop the application using headset button. Note: on some devices the application can be automatically unloaded, if inactive, by the operating system.