If I had an iPod I could use an inexpensive iPod-dock, instead or also.
A complex sound-wave cancelling system is out of my price-range this year.
But I bought a year's subscription to Pandora (for $36) to complement the boom-boxes (that, thriftily, I found by the dumpster) because a while ago someone donated set of speakers for the laptop that were sitting unused. So now I can play non-stop ambient music next to the natural soundscapes, mixing and matching.
The disharmonious din of clunking, banging and rolling that vibrates through the resonant hardwood ceiling in this historic Queen Anne Victorian building, hour by hour, six to twelve hours per day, six days a week (sometimes all seven), becomes concussive to body, mind and soul after a while. Wheeled equipment being shoved around and bumped suddenly into furniture, walls and radiators unavoidably causes the cacophony.
Any sustained sound helps blend out all but the loudest of these astounding shocks, but the too-short sound-loops on many affordable sound-generators only cause a rival (arguably worse) disturbance.
A minority of reviewers of most the better quality sound machines I looked over on Amazon mentioned various functional problems. Some reported noticeable loops and extraneous sounds even when the product description claimed those canned environments were captured in the wilds.
I will soon open (and link up here) a Squidoo lens about the CDs I can recommend for this purpose, so far.
Stand by. I will link to it on the sidebar, too, and include other resources that may help others in this silly situation.
Updated 1/20: Relaxing Nature Sounds is the new lens!