The speech material of the application consists of sound units. These units are presented in the application in two ways.

1. The units are included in a sound dictionary, in which you can search for the units yourself according to various criteria.
2. Exercises are compiled from the units and these exercises are organized into so-called books. There are currently three core books that are structured according to sound phenomena or subject areas. The basic type of exercises are listening and articulation exercises, which have a dual mode: listening and repetition. Another type of exercise is listening exercises with a task, where the user can choose the training or test modes.

Note: Two of these so-called books are also available in printed form (exercise book). In the printed version, the individual exercises contain a QR code, through which the user can open the given exercise directly in the application: Even a user who does not have separate access to the application can use the functions that the application offers for the respective type of exercise for the individual exercises.