照你所说，那还真是郁闷。



MS的waveOutMessage 函数，MM_WOM_FORCESPEAKER 按说明，应该是指切换到扬声器播放,但可能只在已接了耳机，并且音频驱动支持时有效。用于比如接上耳机，又需要在扬声器响铃的地方。由于我现手上没有耳机线，所以也还未测试。

http://msdn2.microsoft.com/en-us/library/ms894688.aspx

In general, when the headset is plugged into a Windows Mobile-based device, all audio should be routed to the headset by default. There are, however, certain sounds, such as the phone ring, that are always most appropriately played through the external speaker so it can always be heard.



Support for the MM_WOM_FORCESPEAKER message is driver dependent. The AR11 sample audio driver implements this message. Hardware that supports selectively routing individual streams to the speaker is rare. So in practice, audio drivers typically keep a reference count of how many streams are to be routed to the speaker. If the number of streams is non-zero then all audio is routed to the speaker.