I was play a pcm(24kHz 16bit) file with AudioQueue, and it mix with other sound( 192kHz 24bit) named sound2.
Setting for AVAudioSession as:
category (AVAudioSessionCategoryPlayback),
options (AVAudioSessionCategoryOptionMixWithOthers|AVAudioSessionCategoryOptionDuckOthers)
when playing pcm the sound2 should pushed volume lower as setting. BUT, there has a absolutly mute keep 0.5 second when the sound2 become low, and after a 0.5s mute the pushed lower sound came out.
It only become in sound2 situation(192kHz, 24bit). if the sound2's quality lower everything is OK.
sound2 was pushed volume lower as it's setting