Flip the headset around and you'll find the earpiece covered in a squishy rubber earbud with a loop attached. There's a very slight tip jutting out at the bottom of the earbud that helps it fit better in the ear, while the attached ear loop helps the earpiece fit within the opening of the ear. We really like these new earbuds--it has a nice secure and snug fit in the ear. There's also an optional ear hook if you prefer, but you don't really need it. The Jawbone Prime comes with earbuds without the attached loop as well. There are three earbud sizes in each style included in the package.
Also at the back of the headset is a tiny little white nub that acts as the Voice Activity Sensor, which is used to amplify your voice. For it to work, you have to wear the headset so that the rubber nub touches your cheek, thus detecting the vibration of your voice. With the Jawbone 2, if you couldn't get the nub to touch your cheek, the sound quality would diminish. However, the Jawbone Prime has a new fail-safe feature that will maintain good sound quality even though the nub isn't touching your face. In fact, the audio will sound just like any other noise-canceling headset. Of course, it's still best to have the Voice Activity Sensor touching your face to get the best voice clarity possible. We actually found positioning the sensor properly was rather easy, as long as you have the right size earbud in place.
We paired the Aliph Jawbone Prime with the Apple iPhone 3G. Call quality was definitely impressive, but not as good as the Plantronics Voyager Pro. We tested the calls in a quiet home environment, a moving vehicle, and on a crowded sidewalk. In the quiet environment, our callers said we sounded loud and clear, with a natural sounding voice and a normal volume level. In the car and on the sidewalk, we sounded a tad softer and a bit muffled, and with a bit of a background hiss, but it wasn't too bad.
We also tested the Jawbone Prime in front of an indoor fan at both low and high speeds. Our voice sounded much softer and much more muffled, and the wind noise sounded like water. However, our callers could still hear us and make out what we were saying. We tested this with our voice mail and verified their claims. Still, the wind noise reduction is not nearly as good as the one on the Plantronics Voyager Pro, and we did definitely have to speak much louder to be heard properly. That said, in normal everyday windy situations, the Jawbone Prime will do just fine. As for incoming call quality, we heard our callers clearly, though there was a slight hiss in the background at times. The callers voice did not sound as full as we would like as well, but that's a minor complaint.