to play these, just compile and run like:

  $> ./f1 > /dev/audio
or (fancier)
  $> ./f1 | aplay
or (fanciest) (this way you can play with the rate)
  $> ./f1 | play -r 8k -t raw -b 8 -c 1 -e signed -
or (fanciester)
  $> ./f1 | sox -r 8k -t raw -b 8 -c 1 -e signed - audio.mp3 # mp3 requires 8khz rate
  $> play audio.mp3