Why Does Javascript Alarm Audio Keep Replaying?

Javascript CountDown Timer: When the timer reaches zero, I want an audio recording to play. I've gotten my audio to play, but seconds after it starts, the same audio plays again with the original audio and it never stops.

Here is my code:

//Javascript Countdown Timer.
//set the amount of time click
//start timer and the clock will
//count down until it reaches zero 
var message = "Complete.";

var parselimit = 0;
var st = 0;
var limit, curhour, curmin, cursec;

function set_limit(strtstop) {
  //prevent multiple settimeouts
  if (st) {
    clearTimeout(st);
  }

  if (document.getElementById("pause").value == 1) {
    limit = document.getElementById("show_timer").innerHTML;
  } else {
    limit = document.getElementById("hours").value + ":" + document.getElementById("min").value + ":" + document.getElementById("sec").value;
  }
  parselimit = limit.split(":");
  // take the minutes x 60 add it to the seconds;
  parselimit = parselimit[0] * 3600 + parselimit[1] * 60 + parselimit[2] * 1;
  //exit if timer wasn't set. //
  if (parselimit <= 0) {
    return;
  }

  if (strtstop == 1) {
    clearTimeout(st);
  } else {
    st = setTimeout("begintimer()", 1000);
  }
}

function begintimer() {
  if (parselimit == 1) {
    //ding ding ding

    ///////////////////////////////////ISSUE STATEMENT//////
    var audio = new Audio('alarmbuzzer.mp3');
    audio.play();

    /////////////////////////Audio Playing///////////////////
  } else {
    parselimit -= 1;
    curhour = Math.floor(parselimit / 3600);
    //alert(parselimit)
    /* greater than an hour divide by
       60 but subtract the hours. */
    if (parselimit > 3600) {
      //first convert hours back into seconds
      curmin = curhour * 3600;
      //subtract that from total to get minutes left.
      curmin = parselimit - curmin;
      curmin = Math.floor(curmin / 60);
      //alert(curmin);
    } else {
      curmin = Math.floor(parselimit / 60);
    }
    cursec = parselimit % 60;

  }
  curmin += "";
  if (curmin.length == 1 || curmin == 9) {
    curmin = "0" + curmin;
  }
  cursec += "";
  //alert(cursec);
  if (cursec.length == 1 || cursec == 9) {
    cursec = "0" + cursec;
  }
  curtime = curhour + ":" + curmin + ":" + cursec;

  //alert(document.getElementById("show_timer").innerHTML);
  document.getElementById("show_timer").innerHTML = curtime;
  st = setTimeout("begintimer()", 1000);
}

function add_time_clock(x, frmelm) {
  var ter = document.getElementById(frmelm).value;
  /* add time */
  if (x == 1) {
    ter = eval(ter) + 1;
    //if greater than 60 go to zero. i'm maxing out the hours at 60 too.
    if (ter >= 60) {
      ter = '00';
    }
  } else {
    /* subtract time */
    ter = eval(ter) - 1;
    //if greater than 60 go to zero. i'm maxing out the hours at 60 too.
    if (ter <= 0) {
      ter = '00';
    }
  }
  ter = "" + ter;
  if (ter.length == 1) {
    ter = "0" + ter;
  }
  document.getElementById(frmelm).value = ter;
}

function rset_tmr() {
  document.getElementById('show_timer').innerHTML = "00:00:00";
  document.getElementById('pause').value = 0;
}

function show_hide(div) {
  if (document.getElementById(div).style.display == 'none') {
    document.getElementById(div).style.display = '';
  } else {
    document.getElementById(div).style.display = 'none';
  }
}

<div id="set_timer" style="">
  <input id="pause" type="hidden" value="0" />
  <br />
  <table border="3" bordercolor="#0047B2" cellspacing="12">
    <tbody>
      <tr>
        <td align="center" colspan="8" height="40">
          <b><span id="show_timer">00:30:00</span></b>
        </td>
      </tr>
      <tr>
        <td>
          Hrs</td>
        <td>
          Min</td>
        <td>
          Sec</td>
      </tr>
      <tr>
        <td>
          <input id="hours" maxlength="10" size="4" type="text" value="00" />:</td>
        <td>
          <input id="min" maxlength="10" size="4" type="text" value="30" />:</td>
        <td>
          <input id="sec" maxlength="10" size="2" type="text" value="00" />
        </td>
      </tr>
      <tr>
        <td>
          [<a href="javascript:add_time_clock('1','hours')" data-cke-saved-href="javascript:add_time_clock('1','hours')">+</a>] [<a href="javascript:add_time_clock('2','hours')">-</a>]</td>
        <td>
          [<a href="javascript:add_time_clock('1','min')">+</a>] [<a href="javascript:add_time_clock('2','min')">-</a>]</td>
        <td>
          <a href="javascript:add_time_clock('1','sec')">+</a>  <a href="javascript:add_time_clock('2','sec')">-</a>]</td>
      </tr>
      <tr>
        <td align="center" colspan="3">
          <input onclick="set_limit()" type="button" value="Start" />
          <input onclick="set_limit('1'),document.getElementById('pause').value=1" type="button" value="Pause" />
          <input onclick="rset_tmr()" type="button" value="Reset" />
        </td>
      </tr>
    </tbody>
  </table>
  <br />
</div>