The third option is to use LG's Voice Guide feature: A synthesized voice shares metrics like heart rate, distance traveled and calories burned directly through the earphones. I don't like how these reports interrupt music playback, and at least you can define exactly which data points will be voiced (there are nine total), as well as the frequency of the voice reports.
Pairing the transmitter to my HTC One (M7) was relatively painless — and much easier than actually getting the earphones into my ears. The asymmetrically designed ear pieces are marked L and R (remember: the sensor is intended for your right ear). But it was always a struggle to get LG's "sharkfin," a stabilizing piece, into the antihelix of my ear, and then wind an ear loop around the rest of my anatomy. The upshot is that LG's earphones are much more difficult to insert than standard earbuds, and positioning is critical, as you'll soon see.
Rotate further for bass drops
For my first few days of testing, I was disappointed with the earphones' sound quality. They produced adequate but not remarkable volume, but the real letdown was a serious lack of bass response. My takeaway was that I might make these my full-time workout earphones just for the heart-rate sensor, but I would miss the lack of low-end thump.
It turns out I wasn't wearing the earphones correctly. You basically have to screw them into your ears, rotating them as far forward as possible in a clockwise motion. If you merely insert them into your ears, without that rotation, you'll still get heart rate data, but none of that essential bass. I'd like to see a troubleshooting note in the user manual FAQ ("How can I improve bass response?"), but I no longer have complaints about sound quality. It's more than sufficient for amped-up, bass-bumping workouts, and can drown out the din of gym equipment.
As for heart-rate data accuracy, I couldn't ask for anything more. My real-time heart-rate numbers scaled evenly and logically as I increased and decreased exertion during sessions on an elliptical machine. Even better, I tested the Heart Rate Earphones against an Adidas Micoach Heart Rate Monitor attached to a NuMetrex Training Shirt, and the LG system matched the chest-sensor system beat for beat. I believe only physicians might need a greater level of accuracy.
How does this thing work?
LG's software is the weak link of the Heart Rate Earphone experience. The LG Fitness app is packed with features for setting heart rate and exercise goals; mapping workout routes over GPS; viewing heart rate in real-time and within various intensity-level zones; digging through the minutia of historical workout data; and much, much more. But the sheer visual density of all these features is dizzying.
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