PLB breathing technique is a method of breathing exercises used as a treatment for easing different medical conditions. The goal of this thesis is the development of a mobile application, designed to playback audio files. Users will be controlling the playing of audio files with their breathing exercises. In order for the application to function properly, the user will have to plug in his/her headset, otherwise breathing detection and, consequently, our application will not work optimally. We have developed this application using Unity for both, Android and iOS operating systems. We have modified our application accordingly to the many differences between the two operating systems.