HarmonyOS 如何监听到音频焦点的变化

如何监听到音频焦点的变化，App内需要监听音频焦点的变化后作出一些对应的响应？

试了以下的代码，createAudioCapturer方法调用时报错 code:6800301,message:system error。

let audioStreamInfo: audio.AudioStreamInfo = {
  samplingRate: audio.AudioSamplingRate.SAMPLE_RATE_44100,
  channels: audio.AudioChannel.CHANNEL_2,
  sampleFormat: audio.AudioSampleFormat.SAMPLE_FORMAT_S16LE,
  encodingType: audio.AudioEncodingType.ENCODING_TYPE_RAW
}

let audioCapturerInfo: audio.AudioCapturerInfo = {
  source: audio.SourceType.SOURCE_TYPE_INVALID,
  capturerFlags: 0
}

let audioCapturerOptions: audio.AudioCapturerOptions = {
  streamInfo: audioStreamInfo,
  capturerInfo: audioCapturerInfo
}

audio.createAudioCapturer(audioCapturerOptions, (err, data) => {
  if (err) {
    console.error(`AudioCapturer Created : Error: ${err}`);
  } else {
    console.info('AudioCapturer Created : Success : SUCCESS');
    let audioCapturer = data;
    audioCapturer.on('audioInterrupt', (interruptEvent: audio.InterruptEvent) => {
      Logger.info('AudioCapturer', 'audioInterrupt' + JsonUtil.stringify(interruptEvent));
      if (interruptEvent.eventType === audio.InterruptType.INTERRUPT_TYPE_BEGIN &&
        interruptEvent.hintType === audio.InterruptHint.INTERRUPT_HINT_PAUSE) {
        //作出对应的响应
      }
    })
  }
});
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