A few years ago I was recording my dulcimer. Nothing computerized - just a mic and a tape recorder. The chap at Radio Shack told me that the hiss on my first tape came from the background noise of the house - the furnace, refrigerator, running water, etc.

On my second try, I turned the fridge up and the heat down. I also chose a time when few cars were going by. The results were far better. I quit recording when my cat, who was huddled atop the only warm thing left in the house (the tape recorder), began to mew piteously.

I would not be surprised if it is still true that you have to turn off background noises even though using computerized equipment.