Making noise for fun and sleeping

I'm a new dad these days and, I guess it goes without saying, sleep deprived. I have a wonderful baby daughter who is otherwise perfect (in my opinion) but who is not fond of sleeping. Which may make her great at all-nighters later in life but is something I'm not too fond of today.

One thing that has helped is having white noise in the background to cover up all of the other sounds going on in the house. I think it also has become part of the routine, so she knows that the background noise means that its time for sleep. There are many ways to make noise, and we've tried running the bathroom fan, or putting the radio on a channel with no station. But my favorite continues to be our white noise CD. It doesn't waste energy (it certainly uses energy, but not as much as a fan) and doesn't waste water (running a faucet).

My noise CD is "handmade" which really means computer made; and not by my computer, but by my students in 5510 from Fall 2006. I assigned them each the task of making a three-minute white noise sound track. And when I say "white noise", I only mean that in the common use of the term.

Actually, white noise is non-white noise. Seriously. I don't mean in the ethnic sense, I mean in the frequency domain sense. Pure white noise, that is, constant power spectral density (PSD) as a function of frequency, is awful to hear. Try it if you don't believe me. If you analyze one of the "Pure white noise" CD tracks on a commercial CD, you'd see that it is emphasizes some frequencies (lower bands) more than others (higher bands).

So the assignment was to design the linear-time invariant (LTI) filter which would produce a good-sounding white noise track, and to analyse the PSD that the filter would produce, using techniques learned in class.

In any case, when I assigned it, I didn't know how valuable these tracks would be for me today. I've probably played on my CD player (on the one-song-repeat option) a white noise track on the order of 10,000 times. So I owe a debt of gratitude to my students.

Since I've been thinking about this CD quite a bit, I thought I'd post and share the link in case someone else would benefit from a white noise CD. The tracks are in MP3 format so they're ready for your standard CD burner software. Your results may vary, and some of these tracks sound quite a bit better (to my ear) then the others, so not all of them are equal -- you might want to select your favorites and only burn those.