since 2013-10-14

arecord -t wav -f S16_LE -c 2 -r 16000 - | aplay -t wav -f S16_LE -c2 -r 16000 -
arecord -t wav -f S16_LE -c 2 -r 48000 - | aplay -t wav -f S16_LE -c2 -r 48000 -

amixer