they are directly below me
Of course they are; and you don't have carpeting, right?
Actually, larryt gave you the answer: sound deadening floor covering, which, as he noted, is usually lead impregnated into, or covered with, something. You may have an issue with its thickness making the table too high, depending on how much height adjustment your table's legs allow, if any.
I don't know what the commercial flooring costs. If that's an issue, you can make your own for very little cost. It's not hard work, just kind of a pain getting stuff rounded up, and a little dangerous. That process is unlikely to interest many people, so I won't go into it here. Let me know if you want to know how.