Where are the vibrations?

You may have experienced that sound is produced by moving a palm of your hand briskly near our ear, by moving a long stick briskly, by jerking a towel, by waving a flag, by clapping, by hitting of a stone on the ground etc. Here you can hear sound but it's hard to see the vibrations.
 
So, it is possible that sound is produced but you cannot see the vibration or vice versa.