wechat-dump/wechat/static/TP_SPEAK.html

<div class="chatItem {sender_label}">
  <div class="chatItemContent">
    <span class="avatar"></span>
    <div class="cloud cloudVoice" onclick="playVoice(event)" style="width:80px">
      <div class="cloudPannel" title="{time}" {nickname}>
        <div class="sendStatus">
          <span class="second">{voice_duration}"</span>
        </div>
        <div class="cloudBody">
          <div class="cloudContent">
            <span class="icoVoice"></span>
            <audio>
              <source src="data:audio/mp3;base64,{voice_str}" />
            </audio>
          </div>
        </div>
      </div>
    </div>
  </div>
</div>