Download audio file from html with javascript function

I’m trying to download an mp3 file on the click of a button, it downloads, but the file it downloads is not correct, it’s a WAY smaller file than the original one (25 bytes), while the original one is 10MB.

It’s my first time working with downloading stuff so I’m pretty clueless.

Here’s some code:

JS function:

 function download(i) {
    var audio = document.getElementById("audio"+i);

    const blob = new Blob(, {type:"octet-steam"});

    const href = URL.createObjectURL(blob);

    const a = Object.assign(document.createElement("a"), {
        href, 
        style: "display:none",
        download: "myAudio.mp3",
    });
    document.body.appendChild(a);

    a.click();
    URL.revokeObjectURL(href);
    a.remove();
}

Audios are identified by their ID and their file name comes from the data I have in a database.
HTML/PHP

for($i=0; $i<$count; $i++){
  $res = mysqli_fetch_array($result);
  echo('<tbody id="tbody">
  <tr>
  <audio id="audio'.$i.'" src="mp3/'.$res["song_artist"].'-'.$res["song_title"].'.mp3"> 
  <td><button onclick="download('.$i.')">&#8628</button></td>
  </tr>
</tbody>');
}