Which of the following condition would decrease the ability of a person to hear a sound?

These are some conditions that can possibly decrease the ability of person to hear a sound:
1. Blockage of the ear canal -  ear wax is naturally produced by our ear canal which serves as self- protection. It also block sounds if the ear canal is not well cleaned. 
2. Foreign bodies in the ear canal - foreign bodies such as beads, left residue of cotton, peas or even small insects like bugs, bees, and spiders. 
3. Infected Eardrum - eardrum catches sound waves that passes through the ear canal. If the eardrum is damage, it may lessen its ability to catch sound effectively.