Yes, you can get these sounds from a lot of sites. Theses are called binaural beats. Ok, so as you may now your brain has different frequencies throughout the day like 40MHz when you're awake and doing something and something like 20MHz when you're lying down relaxed, and about 5-9 when you're in Rem sleep. (My numbers may be way off by the way, this is just kind of an example.) But what binaural beats do is play two frequencies, one in each ear, so yes you do NEED headphones, and the difference between them is what goes into your brain. For example, one hear plays 130MHz and the other plays 123MHz the the difference between them is 7MHz, which is what enters your brain. Now, I haven't had any LD's with that, but it's good for meditating, and relaxing. I had a REALLY vivd dream with them, but they actually ruined it, because the sounds entered my dream causing me to wake up.