(MONEY Magazine) – You might think, "Who really needs a Bluetooth headset?" Well, do you drive? Do you like having the use of not one but two arms? If so, maybe a headset isn't such a crazy idea after all.

Bluetooth (named after a 10th-century Scandinavian king, in case you were wondering) is a technology that lets different electronic devices "talk" to each other using a short-range radio signal. With a Bluetooth headset you can talk on your mobile without actually holding it in your hand. (If you're driving, this is a much safer and better solution than juggling handset and steering wheel or using a mediocre speakerphone.) You don't even have to keep your phone on your person. Leave it in the backseat or in your briefcase--as long as you're within 30 feet, you can reach out and touch someone.

The latest headsets improve on the limitations of Bluetooth's first generation: They're less bulky, more comfortable and easier to use. Some models now have such extra features as noise cancellation, which reduces background sounds around you to ensure that your voice comes in loud and clear. Headsets are also cheaper, starting at around $35.

Finding a good headset for all conditions, however, can be tricky business. A few work like gangbusters in a quiet office, but out on the street they'll pick up every sound within a 20-foot radius. Others block out so much noise that they wind up muffling your voice as well.

I took five popular models to New York City's Acoustilog sound lab. The lab directed 65 decibels of sound (normal conversation) toward each headset from three inches away to measure how much of your voice the microphone picks up. To test how much noise the headsets block, the lab blasted 85 decibels (heavy traffic) toward them from six feet away. For a more real-world test, I also tried each one out on some noisy city streets.

HOW I DID IT New York's City's Acoustilog tested the headsets' sound capabilities. I took them to Times Square and other tourist spots to see which one stood out from the crowd.

WHAT TO LOOK FOR

You could spend hours on the phone with the Jabra BT500 because:

• It feels comfortable and secure on your ear.

• The buttons are easy to navigate, and it turns on quickly.

• It's loud and clear in a quiet room or on a noisy street.

TIP

Position can sometimes affect Bluetooth reception, so it's a good idea to keep your phone on the same side of your body as the headset to prevent calls from breaking up or getting too fuzzy.