First they came for your wrists. Next they came for your eyes. Now the wearable tech manufacturers are coming for your ears.

The Freewavz earphones can track your heart rate and share your exercise data via a synthesized voice just like the LG Heart Rate Earphones I reviewed earlier this month. But unlike LG’s product, this new Kickstarter project does away with messy wires and uses a pulse oximeter sensor to divine heart rate and blood oxygen saturation data.

Freewavz showed us the rough prototype you see here, but a fully polished version is slated to ship to Kickstarter backers in Octover for $179.

The Freewavz inventor—an ear, nose and throat doctor named Eric Hensen—says this sensor offers improved accuracy relative to a more rudimentary spectroscopic approach employed by LG.

Specifically, Hensen says, LG’s sensor is just a single-piece affair. It shines a beam of light at blood vessels and measures what’s been reflected to determine heart rate. But the Freewavz oximeter depends on two pieces, just like equipment used in hospitals. It shines light through the thin tissue of your earlobe, and measures that light after it hits a photodetector on the other side.

Image: FreeWavz The FreeWavz sensor (above) uses the same two-piece approach of a hospital-grade oximeter, shining light through the thin tissue of the earlobe.

“In the operating room, I can’t have errors when my patients are asleep,” Hensen told TechHive. “I need to know what they’re doing all the time. So I took this particular technology, and applied it to what we’re doing. A through-the-tissue approach is more accurate. This is the same way we do it in the OR. We’re measuring blood flow and oxygen that’s bound—or, in this case, not bound—to hemoglobin.”

It’s worth noting that I found LG’s Heart Rate Earphones to be as accurate as a chest-strap heart rate monitor—a standard-issue gadget that many exercise enthusiasts are already familiar with. But the FreeWavz blood-saturation data could be of interest to more hardcore athletes.

Most people, even during the heat of exercise, maintain saturation levels between 97 and 100 percent, so real-time data reports that dip below 95 percent could signal over-training or a serious medical problem.

The FreeWavz earphones also include an accelerometer to track your steps. That’s a trick that’s currently unavailable in LG’s ear wearable.

They play music too

Earphones being earphones, the FreeWavz play audio just like any other earphone product. But Hensen and FreeWavz president Harry Ericson have added some extra convenience features to make the earphones more compelling.

First off, the FreeWavz are completely wireless. Thanks to the latest Bluetooth technology, the left and right earphones (which are packed with identical hardware) form a wireless connection with each other. Similarly, one of the two earphones assumes a master relationship with your smartphone to wirelessly stream audio from that source. What emerges is a system that’s particularly liberating, with no messy wires dangling from your ears or leashed to your phone.

Image: Jon Phillips You can plainly see how the EarWavz hardware rests against both sides of one’s earlobe.

Each earphone weighs 1.5 ounces, and the system is rated for 6 to 8 hours of battery life. I found the FreeWavz to be surprisingly light, and couldn’t dislodge them from my ears no matter how hard I shook my head. I didn’t get a chance to test audio quality, as I was only handling the rough prototype pictured in the images above.

Fitness updates and ambient noise control

The FreeWavz can report various fitness metrics—heart rate, distance, oxygen saturation, and more—directly through their speakers in a synthesized voice. You can set an accompanying smartphone app to issue these reports according to set time intervals, or in response to a trigger, like when your heart rate increases by 10 beats per minute. A press of a physical hardware button can share your data on demand.

Image: FreeWavz Choose which bio-data metrics you want voiced through the earphones’ synthesized voice.

The system also includes two microphones on each earpiece to pick up not only voice commands for smartphone control, but also ambient noise for what FreeWavz calls “environmental listen-through.”

In a nutshell, this feature mixes music from your smartphone with noise from the world around you. For example, if you’re working out with free weights at the gym, it’s probably safe to set your music at 100 percent. But if you’re cycling on the shoulder of a busy highway, you might want 25 percent music and 75 percent ambient noise in your left earphone to hear approaching cars. These ratios can be adjusted in the FreeWavs mobile app.

Another cool feature provides a volume governor to protect against hearing loss—because, remember, Dr. Hensen is an ear, nose and throat guy, and he cares about this stuff. The system can get as loud as 120 decibels (and that’s very loud), but an algorithm will only maintain excessive volumes for a duration that’s proportionate to the risks they pose.

The FreeWavz Kickstarter campaign is looking for $300,000 in pledges in the next 43 days. Backers will get the FreeWavz hardware for $179, and the company expects a final retail product to sell for about $300. Ultimately, the success of a product like this will come down to the accuracy of its bio data, the quality of its audio, and the overall ease-of-use of its hardware and software. A lot can go wrong in such a complex system, but if LG’s earphones tell us anything, it’s that FreeWavz is moving in the right direction.