Why do computers hum?

If you've ever been in the same room as a computer you're most likely already familiar with the gentle hum you often hear from the machine. Some are loud, some are quiet, some change pitch as if singing along to their own digital music in their proverbial heads, but why? What exactly is it in the mysterious jumble of parts and cables that makes that sound?

There's no one answer. The sound we most commonly hear the loudest are fans. Remember how we talked about computers running on electricity to make all those ones and zeros? Well, if you've ever touched a lightbulb that's been on for awhile or grabbed your toast out of the toaster too soon you know that electricity makes things hot. Know what delicate computer parts don't like? You guessed it- heat! That's why if you live in a warmer climate like Florida (Hi, Mom!) you're more likely to hear your computer's fan kick on and go faster than if you live in cooler climates like Central New York like me. That's the humming sound that sometimes winds down after awhile or kicks on after you've been using your computer long enough to be startled by it suddenly sounding like it wants to fly away.

Another, usually quieter sound you may hear is the hard drive spinning. The hard drive is a lot like a miniturized record player. It has discs in it that spin at amazing rates and are read by a play head. While a vinyl record may spin at about 30-45 rpm (rotations per minute), the average hard drive in a computer spins anywhere between 5400-7500 rpm. It's this spinning that sometimes causes the humming sound you hear, especially if it starts while you're trying to start a program or open a file.

Practical Tip of the Day:
If you notice your computer humming particularly loudly, you should check the back of your computer tower (if you're using a desktop computer) and see if you have "junk in your trunk". Computer fans are just like ceiling fans and can pick up lots of dust and dirt on the blades. If the fan looks dirty, use some canned air to spray it off. If your fan gets too dirty, your computer can overheat and cause problems for you later on.