alps\frameworks\base\packages\Keyguard\src\com\android\keyguard\KeyguardViewMediator.java
#1384 行左右：
///M: [ALPS00827994] always to play sound for user to unlock keyguard
mSuppressNextLockSound = false;
修改：
///M: [ALPS00827994] always to play sound for user to unlock keyguard
if (authenticated) {
mSuppressNextLockSound = false;
} else {
mSuppressNextLockSound = true;
}
android 连接USB按power键锁屏2声锁屏音
原文：http://blog.csdn.net/sergeycao/article/details/40826543
