You'll need to cache a reference to that Audio instance so you can do more stuff to it. For example:
var song = new Audio(...);
$(document).on('click', '.audio tw-link', function () {
song.play();
});
$(document).on('click', '.audio-stop tw-link', function () {
song.pause();
song.currentTime = 0;
});
You'll notice that I changed the selectors to '.class tw-link'. So you'd move your spans out of the link markup to use this, which is safer than putting them inside the markup:
<span class='audio'>[[link]]</span>
Also, I have heard that creating an actual <audio> element (with jQuery, probably) rather than using the Audio constructor is better, but someone more knowledgeable than me would probably know more about that.