1. Hearing Loss

2. There are four types of hearing loss, as follows (eHealthMD, n.d.):
Conductive hearing losses are caused by diseases or obstructions in the outer or middle ear (the pathways for sound to reach the inner ear). Conductive hearing losses usually affect all frequencies of hearing evenly and do not result in severe losses. A person with a conductive hearing loss usually is able to use a hearing aid well or can be helped medically or surgically.

3. Sensorineural hearing losses result from damage to the delicate sensory hair cells of the inner ear or the nerves that supply it. These hearing losses can range from mild to profound. They often affect the person’s ability to hear certain frequencies more than others. Thus, even with amplification to increase the sound level, a person with a sensorineural hearing loss may perceive distorted sounds, sometimes making the successful use of a hearing aid impossible.

4. A mixed hearing loss refers to a combination of conductive and sensorineural loss and means that a problem occurs in both the outer or middle and the inner ear.
A central hearing loss results from damage or impairment to the nerves or nuclei of the central nervous system, either in the pathways to the brain or in the brain itself.

6. Prelingual deafness From Wikipedia, the free encyclopedia
A "prelingual deaf" individual is someone who was born with a hearing loss or someone whose hearing loss occurred before they began to speak. Infants usually start saying their first words around one year, therefore for a child to be considered prelingually deaf, they would have to have lost their hearing before age one (which is the age at which the majority of hearing losses in children occur). Congenial hearing losses are those that are present at birth, but a child with a congenital hearing loss is also considered prelingually deaf since a newborn infant has not acquired speech and language capabilities yet.

7. Causes
Prelingual hearing loss can be either acquired, meaning it occurred after birth due to illness or injury, or it can be congenital, meaning it was present at birth. Congenital hearing loss can be caused by genetic or nongenetic factors.

8. Causes
The nongenetic factors account for about one fourth of the congenial hearing losses in infants. These factors could include: Maternal infections, such as rubella, cytomegalovirus, or herpes simplex virus, lack of oxygen, maternal diabetes, toxemia during pregnancy, low birth weight, prematurity, birth injuries, toxins including drugs and alcohol consumed by the mother during pregnancy, and complications associated with the Rh factor in the blood/jaundice.

9. Post-lingual deafness is a deafness which develops after the acquisition of speech and language, usually after the age of six.

10. Causes
Genetic factors account for over half of the infants with congenital hearing loss. Most of these are caused by an autosomal recessive hearing loss or an autosomal dominant hearing loss. Autosomal recessive hearing loss is when both parents carry the recessive gene, and pass it on to their child. The autosomal dominant hearing loss is when an abnormal gene from one parent is able to cause hearing loss even though the matching gene from the other parent is normal.