public Builder setStartOffset(com.google.protobuf.Duration.Builder builderForValue) {
      if (startOffsetBuilder_ == null) {
        startOffset_ = builderForValue.build();
      } else {
        startOffsetBuilder_.setMessage(builderForValue.build());
      }
      bitField0_ |= 0x00000001;
      onChanged();
      return this;
    }
<pre>
Time offset relative to the beginning of the audio,
and corresponding to the start of the spoken word.
This field is only set if
[enable_word_time_offsets][google.cloud.speech.v2.RecognitionFeatures.enable_word_time_offsets]
is `true` and only in the top hypothesis. This is an experimental feature
and the accuracy of the time offset can vary.
</pre>

<code>.google.protobuf.Duration start_offset = 1;</code>
java-speech/proto-google-cloud-speech-v2/src/main/java/com/google/cloud/speech/v2/WordInfo.java