sounds are sounds you make by vibrating your vocal chords. You do not use
your vocal cords for unvoiced sounds - You use air only. To feel the
difference between voiced and unvoiced sounds, hold your throat lightly and
say the sound vvv. You will feel your vocal chords vibrating.
Then, without pausing, change the sound to fff. The vibrations will
stop. The only difference between the sounds is that the vvv is
voiced and the fff is not.