Children should be able to speak clearly and understandably by: One year old.
Two years old.
Three to four years old.
Four to five years old.
After five.

Ifound this on google “your outer ear collects sound waves and reflects them into a tiny tube called the ear canal. at the end of the ear canal is a thin, skin-like membrane stretched tightly over the opening, called the eardrum.” i hope this you for what your looking for

My answer is opptionc, just check with anyone else