当手机进入睡眠模式，所以没有CPU。有些recievers可以唤醒手机造成你的声音被听到。看看进入 PowerManager的并尝试唤醒您的手机（及CPU） ，当您想听的声音。

When the phone goes into sleep mode, so does the cpu. Some recievers may wake the phone up causing your sounds to be heard. Take a look into PowerManager and try to wake your phone(and cpu) up when you want to hear the sound.