title: AudioQueue volume too low
body: <p>I am having a problem when using AudioQueue to play PCM data. The volume is low when using the iPhone's speaker; I have even turned the system volume up to maximum. However, the volume is fine when I am using the earphones.</p>
  
  <p>I inserted the data into the queue like this:</p>
  
  <pre><code>    memcpy(mBuffers[mIndex]-&gt;mAudioData, pcmData, mBufferByteSize);
      mBuffers[mIndex]-&gt;mAudioDataByteSize = mBufferByteSize;
      mBuffers[mIndex]-&gt;mPacketDescriptionCount = mBufferByteSize/2;
      OSStatus status = AudioQueueEnqueueBuffer(mQueue, mBuffers[mIndex], 0, NULL);
      NSLog(@"fill audio queue buffer[%d]",mIndex);
      if(mIndex == kNumberBuffers - 1) {
          isStartPlay = YES;
          mIndex = 0;
          AudioQueueSetParameter(mQueue, kAudioQueueParam_Volume, 1.0);
          status = AudioQueueStart(mQueue, NULL);
      }else {
          mIndex++;
      }
  </code></pre>
  
  <p>I have set the volume like this:</p>
  
  <pre><code>    AudioQueueSetParameter(mQueue, kAudioQueueParam_Volume, 1.0);
  </code></pre>