Plantronics is launching a Bluetooth headset today with one cool feature: It knows when it is hanging on your ear.

When you place the Voyager Pro HD headset on your ear, the sensors on the device can tell whether you’re wearing it or not. If you are, the headset automatically answers the call on the headset speakers and microphone. If you are not, the device allows you to answer the phone using the phone’s microphone and speakers. When you take it off your ear, it will pause an audio stream and it will lock the call button to avoid accidental redials.

This kind of smart device offers cool benefits to users and justifies a higher cost, separating it from the pack of other headsets on the market. In that respect, the approach is similar to the higher-priced Jawbone headsets on the market. The new Plantronics headset also shows that if you attach a sensor to just about any device, you can turn it into something with a higher value and new functions.

The device can handle streaming high-definition audio and uses Plantronics’ Vocalyst voice-recognition service to let you manage email, check the weather, or update Facebook using voice commands. The Plantronics MyHeadset app gives you tips, tricks and tools for Android.

If you triple tap the Call button, the headset dials Vocalyst, the voice and text service, which can read your text messages to you while you drive. You can stream music, podcasts, directions, and other audio to the headset. Voice alerts can tell you how much talk time is remaining. You can monitor your headset battery level on the iPhone or Android smarphone. The headset sells for $99. It weighs 17 grams and can run for six hours of talk time and five days of standby time.