Welcome to Librivox, Kristyna!
Your voice is pleasant and animated and your test meets all the Librivox technical standards. I don't notice an annoying beep in the background at all. Is it possible it's a sound that you're hearing, but that isn't being picked up by your mic? I find that some sounds just don't make it into my recordings (for example, my husband practicing his guitar in another room just doesn't seem to get picked up, even though I can hear him).
The only thing I do notice is that there are some pronounced plosives (pops) on your P sounds and a few soft brushing sounds as if you're touching your mic. You can prevent those by speaking to one side of your mic rather than straight into it, at a distance of about 6 inches.
Why don't you try re-recording the test using that method to see if that eliminates these sounds before you get started? I'll come back and check it out.
Thanks,
