arecord -D hw:0 -r 44100 -c 2 -f S16_LE | aplay -

or possibly:

mplayer -tv driver=v4l2:width=640:height=480:outfmt=i420:alsa:adevice=hw.0: amode=2:audiorate=44100:forceaudio:immediatemode=0:norm=PAL tv://