My SDL audio app silence when start another player app

I use SDL auido functions,such as SDL_OpenAudio, SDL_PauseAudio, etc, to play audio pcm data on Windows platform in my app. Normally, the app work finely! But when I start other apps that use audio driver(for example mp3 player), my app will silence except for make my app in top window. How to solve this problem?

any suggestion is helpful for me.