This medical term [hypoacusia] is composed of the prefix [ hyp-], a derivate from the Greek [υπό] (ip? which means "under", "deficient" or "below". The root term [-acus-] is also a derivate from the Greek [ακούω] (ako?o?) meaning “listen”, or “hear”. The adjectival suffix [-ia] has a double meaning of “pertaining to” and “condition”. The term hypoacusia means then “a condition of deficient hearing”. It can also be used as [hypoacusis] with the same meaning.
A common mistake is to use this term for total deafness. This is not correct, in [hypoacusia] the patient has varying degrees of hearing loss, but there is some hearing function left.
There are many causes of hypoacusia: genetic, viral, bacterial, traumatic, etc. There are two types of hypoacusia. The first one is transmission hypoacusia, where the mechanical system that transmits vibration from the external ear and tympanic membrane (eardrum) to the inner ear can be damaged. The second type is neurosensory hypoacusia, where the components of the inner ear as well as the nerve structures of the vestibulocochlear nerve (VIII cranial nerve) up to and including brain areas related to the hearing process may be damaged.
Different degrees of hypoacusia have been demonstrated to affect proper communication functions and learning. Lower levels of hypoacusia (less than 25%) can be undiagnosed in small children; in fact, there are several studies that prove that the presence of low level hypoacusia in small children is a good predictor of language alteration and learning problems if not diagnosed properly and timely.
My personal thanks to Maria E. Gallegos, Chair of the Speech Pathology School, Iberoamerican University, Santiago Chile, for her help in this article. Dr. Miranda