May damage the eardrum and bones of the middle ear. earwax a. earwax b. harmful noises c. hammer d. anvil

I'd say earwax. it can become impacted and bother the tympanic membrane (eardrum)

harmful noises can damage your hearing but that's more in the inner ear.

the hammer and anvil are terms for the malleus and indus respectively which are two of the three bones in the middle ear. they transfer the physical impact from the tympanic membrane to the oval window of the inner ear. unlikely they cause damage.

Efficiency is an act of doing something

That would be kinetic energy