The occasional rumbling sound in your ear is not a motorboat, but a muscle contraction initiated to protect against loud sounds. Sound waves are collected by the outer ear (pinna) and travel down the ear canal to the eardrum (tympanic membrane). The eardrum vibrates, as the sound waves reach it, conducting the sound to the middle ear cavity which houses our three smallest bones: hammer (malleus), anvil (incus), and stirrup (stapes).
These three bones with tiny muscles attached vibrate against the oval window leading to the inner ear (cochlea). The two muscles in the middle ear cavity are the tensor tympani and the stapedius muscle. When sound is excessively loud, the tensor tympani contacts which pulls the malleus away from the eardrum, dampening the sound. This dampening effect in the ear can cause a rumbling sound.
Even in healthy ears, this rumbling sound can also be noticed from chewing, coughing, yawning, or yelling. Some people can willfully cause ear rumbling. But be wary, a rumbling sound can also be caused by an ear infection or Meniere’s disease. A doctor’s consultation is warranted if you experience a fever, balance problems or the sounds are so annoying that they prevent daily activities.