使用VoiceProcessingIO音频单元子类型而不是RemoteIO会导致不必要的输出音量下降

I am using RemoteIO in my voice chat application. To enable echo canceling, I changed "kAudioUnitSubType_RemoteIO" to "kAudioUnitSubType_VoiceProcessingIO" after setting "kAudioSessionCategory_PlayAndRecord" as the session type. Now echo canceling works but the output volume level has dropped significantly versus the previous RemoteIO output level. Does anyone know how to get the same output volume level when using VoiceProcessingIO as when using RemoteIO?I am using RemoteIO in my voice chat applicatio