Please close this bug, I found a workaround. It is just because the webcam's microphone was not set to default in pulseaudio configuration. Executing: pactl "set-default-source alsa_input.usb-046d_09a4_F89C6650-02-U0x46d0x9a4.analog-mono" resolves the issue. Can be made persistent in /etc/pulse/default.pa. (Command not documented in 'man pactl') The message "Unlikely big volume range" in syslog is just cosmetic. Ingo