This trial version will only display the last 2 training pages (14 & 15) of Level 1a. This should give you an idea of how it works without taking too much of your time -- perhaps 3-5 minutes of training.
The full version have Training Levels: 1a, 1b, 2a, 2b, 3a_1, 3a_2, 3b_1, 3b_2, 4a__1, 4a_2, 4b_1, and 4b_2. Naturally, the levels start off easier and get more difficult as your 'auditory discrimination' improves with neurological synapses growth. The first few levels have 15 training pages. The more difficult, higher levels, have fewer.