public com.google.protobuf.ByteString getAudioTopicBytes() {
      java.lang.Object ref = audioTopic_;
      if (ref instanceof String) {
        com.google.protobuf.ByteString b =
            com.google.protobuf.ByteString.copyFromUtf8((java.lang.String) ref);
        audioTopic_ = b;
        return b;
      } else {
        return (com.google.protobuf.ByteString) ref;
      }
    }
<pre>
Description of the content. Eg. "Recordings of federal supreme court
hearings from 2012".
</pre>

<code>string audio_topic = 10;</code>

@return The bytes for audioTopic.
java-speech/proto-google-cloud-speech-v1p1beta1/src/main/java/com/google/cloud/speech/v1p1beta1/RecognitionMetadata.java