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That's just gratuitously negative and dismissive. Bluetooth 4 is actually not bad at all in my experience. Pairing is painless relative to old versions; sound quality is flawless; connections are quite reliable. The "strain" is to be expected around other devices since Bluetooth uses 2.4GHz, a very crowded band. I can't speak to the technical bits since I never looked at them, but my experience as a consumer has been…
> sound quality is flawless; I have a headset that supports Bluetooth 3 only and audio quality is bad (especially while making calls where it chooses the HFP profile which is the only one where the mic is available). I vouched to never again buy any Bluetooth audio devices. Are you saying Bluetooth 4 would actually solve my problem? Should I still have hope?
Make sure your headset and device (phone?) both support HFP1.6 or above (which supports wideband speech/HD voice) which makes the sound quality semi-decent