To change the sample rate and audio bit depth we need to edit the configuration file for the pulseaudio server /etc/pulse/daemon.conf.
Please backup the original settings to restore the defaults in case som settings break your audio.
Look for the following entries:
; default-sample-format = s16le
; default-sample-rate = 44100
Both are commented out with ;. This means they are not read as the entries given here are the defaults. Uncoment them and replace them with values that suit you better. Always keep in mind that this may be on cost of system performance or stability when choosing extreme values.
Possible entries for the sample format are: u8, s16le, s16be, s24le, s24be, s24-32le, s24-32be, s32le, s32be float32le, float32be, ulaw, alaw
Possible entries for the sample frequency are anything between 1 and 192000 Hz (choose sensible values!)
Save this file as ~/.pulse/daemon.conf or in it's original location (you need to be root then). In order for changes to take effect pulseaudio needs to be restarted with pulseaudio -k in a terminal, or by log out and log back in.