I had similar issues with my SHB9000 and windows 7 x64 and though they seem resolved now that I installed the latest ASUS Bluetooth drivers, I did notice some interesting things;
1) The ACER bluetooth drivers did install, but messed up everything. All the devices exposed by the headset were there all the time, even when the headset was off, and the sound defaulted to it all the time even if it was nowhere near the laptop. The drivers installed fine though, no conflicts.
2) The ASUS drivers, specific for the BT-253 chipset, worked fine, even though the ACER ones claimed to be a newer version (I had to manually uninstall both the software and all drivers).
3) Most importantly, while experimenting, I noticed that the headphones switch from the proper stereo protocol (A2DP) to the crappy wireless headset one (the mono sound, whatever the name is) whenever I activated the microphone in some way or another. Currently, the headset is present as both a playback and recording device in the audio settings, whenever it is turned on. The recording device is the default recording device when the headset is turned on. As soon as I turn on ANYTHING that captures microphone input (even the "Recording" tab in the "Sound" settings), it switches to mono sound in order to enable microphone input. If I DISABLE the wireless microphone, or switch the default to the built-in microphone, it goes back to proper stereo sound.
In short; if you're experiencing this, try disabling the wireless microphone in the sound settings, or set the default one to another microphone. As long as the microphone on the headset is not in use, it will use A2DP and the sound quality is fine.
Best Answer
After some investigation, seems like
pulseaudio-module-bluetoothis missing. These are the steps to install it:This should be enough. No need for a reboot.
EDIT 1:
Not all headsets allow simultaneous hi-fi output sink and input source, i.e.: there are different profiles (a2sp, hsp, hfp) which may or may not be supported simultaneously. The "problem" is that a single Bluetooth channel has not sufficient band for both communications to occour simultaneously. Only "dual channel" headsets support different profiles simultaneously.
I cannot tell for sure, but my Philips SHB9850NC was not able to play well with HSP profile: the microphone was simply not working. I was not able to figure out what the reason was. I've tried to switch profiles and I've tried lots of things for a fair amount of time. I cannot claim that "it does not work": maybe it was just my plain incompetence to make it work on Linux... but it shouldn't be rocket science, right?
I've ended up buying another headset (a dual channel) which comes with a pre-paired USB dongue which supports multiple profiles simultaneously.
If you are looking for a headset for videoconferencing over WebRTC for example, you'd better try brands/models targetting this specific market, advertising very clearly this specific usage on call centers or other business applications.
EDIT 2:
Thanks @Hannu for pointing out a script which helps select device profiles:
https://gist.github.com/pylover/d68be364adac5f946887b85e6ed6e7ae
EDIT 3:
Enabling the equalizer: https://gist.github.com/frgomes/5ff8fd34e25d5297517f86ce77ba7fca