my bluetooth audio doesn't sound good in ubuntu

$ sudo rm /var/lib/bluetooth/cache/*
$ dmesg | grep -i bluetooth
$ dmesg | grep -i bluetooth | grep -i firmware
$ lsub
$ sudo apt-get update
$ sudo apt-get install blueman
$ pactl list | grep -i bluetooth
$ pulseaudio --k
$ pulseaudio --start
$ init 0