AS we age our hearing deteriorates and typically it falls in the area of high pitch sounds.
Everyone is different though, but this is the norm.
Some individuals cannot hear high pitch which is is very common, some fall in the speech sounds , rarely so and this must be the worst, thirdly as for myself we cannot hear the low sounds...maily men, recordings, and vidoetapes, T.V, lyrics to words but the music is still awesome.
There are many underlying factors that contribute to hearing loss ie., genetics, virus, diabetes,(immunizations, an allergic reaction to), and I have read recently parasites can play a part as well.
I cannot recall the exact year that it was discovered that many babies were affected by the incubators and too much oxygen was released while they were in there for whatever reason and it caused hearing loss! I think it was discovered in the early 60's or late fifties.
I have met many people that have lost their hearing and some even lost sight due to an allergic reaction to immunization shots and they became deaf/ blind as well..even CP . (Cerebral palsey.)
The mother also can contract a virus and give it to the unborn child and many problems can occur from this as well.
Some of the worst cases can come from the unborn child while in the womb and have a bowel movement and this is very dangerous and can result in blindness, deafness, and a host of problems can result from the bacteria of feces in the sac.
There is more... a virus went through our town about 2o years ago and several teachers lost their hearing, some their sense of smell!!! One teacher lost hearing in both ears and the other lost it in one ear. One teacher lost her sense of smell.
Once they contract the virus, it is irreversable as it attacked the nerves and nerves cannot be cloned.