I've released a desktop app called Chanter. It's a tool for people who'd like to improve their meditation or mindfulness skills, which gives instant audio feedback about your state of meditation. In short, the app plays a mantra-like audio loop, and changes the pitch of the loop according to the meditation level of the user.
You need a NeuroSky headset, the MindWave or Mindset, to make this work. The headset registers brainwaves - EEG - that are sent to the computer wirelessly, using a dongle that comes with the headset, and a small software program that you need to install.
Seantheflexguy was the first developer who made me aware of this exciting hardware, and he also wrote an open source ActionScript 3.0 API, making it simple to hook up the headset to a Flash or AIR project. Actually I'm not using that API, as NeuroSky also provides some brief and clear instructions on making Flash listen for messages from the headset.
Brainwaves and level of meditation
The messages returned by the NeuroSky software are not only the delta, theta, alpha, beta and gamma bands of the EEG, but also two values that are based on these bands: concentration and meditation. Obviously, Chanter listens to the meditation value, although concentration and meditation are not opposites; the 'ideal' state of mind would be a value of 100 for both categories.
There are quite a few apps in the Neurosky store, most of them simple games, with an emphasis on mind exercise. The one that - in my opinion - stands out is another meditation tool called Dagaz. What struck me though is that all available apps are based on the idea of visual interaction, in other words: you need to look at your computer screen while experiencing the tool or playing the game. My next thought was: wouldn't it be nice to build a meditation tool that is based on audio only, so that you don't have to look at your screen when meditating, a tool that even allows you to close your eyes? This idea resulted in Chanter.
A promotional website can be found here, and the app is available in the NeuroSky webstore. Below are a couple of screenshots of the app.
Pitching the mantra loop
The code for changing the tone of the mantra mp3 that the user selects is derived from a class by (surprise, surprise) Andre Michelle. It's not real pitch shifting, which would mean maintaining the same tempo, but it suffices for the short loops that I'm using.