QT Screens sound problem on Raspberry Pi 3 Board

Our QT QML Screens run on Raspberry Pi 3 board has sound play problem. screens should play BGM and button sound effect. but when I touch buttons, button effect sounds are not played properly. I feel it is jammed or blocked by some reason. check attached QT source files and apply this project only If you can handle it. you MUST have RP3 board and cross-compile to check sound problem on RP3 board.