All sound is vibration, so everything is affected by sound at some point as the vibrations propagate through and physically move around materials. Humans can hear because the audible frequency range moves receptors in human inner ears, and as you can imagine this isn't local to the ear, the whole brain will be affected (but biology has accounted for this). If you knock on wood that sound is audible in many frequencies--below human audible, audible and also above human audible (what we call 'ultrasound'). What is more dangerous generally is sustained noise at any frequency; lower frequency + high amplitude is one of the most harmful as that can physically push you.