How Hearing Works

Types & Degree of Hearing Loss

Hearing loss can impact one ear, known as unilateral, or both ears, termed bilateral. Hearing loss is also classified into different types depending on where it occurs in the ear. Below are descriptions of the main types of hearing loss.

1. Conductive hearing loss is caused by problems in the outer and/or middle ear. Sound waves have trouble reaching the inner ear. This can be due to issues such as earwax buildup, fluid in the middle ear, or problems with the ear canal, eardrum, or middle ear bones. Treatment for conductive hearing loss often involves medical intervention or surgery to address the underlying cause.
2. Sensorineural hearing loss is caused by a change in the inner ear or auditory nerve. This happens when some of the delicate hair cells in the inner ear cannot convert sound into electrical signals. Sometimes the nerve is damaged which makes it hard for sound to reach the brain. This type of hearing loss in children is commonly caused by genetic factors, virus, or certain medication. Sensorineural hearing loss is typically permanent. Hearing aids may be recommended for this type of loss. Cochlear implants may be an option if the loss is more significant.
3. Mixed hearing loss is a combination of both conductive and sensorineural hearing loss. This means there may be problems with both the outer or middle ear and the inner ear or auditory nerve. Treatment for mixed hearing loss depends on the specific combination of factors involved and may include a combination of medical interventions and hearing devices.
4. Auditory neuropathy (AN) is a condition in which sound enters the inner ear as expected but the transmission of signals from the inner ear to the brain is impaired. AN is unique in that children may be able to detect very soft sounds but still have a hard time understanding speech clearly. Sounds may fade in and out and seem out of sync, especially in background noise. Because of this, it is sometimes called auditory “dys-synchrony”. Cochlear implants may be an option for this type of hearing loss.

Each type of hearing loss described above can be more or less severe. The severity of hearing loss is called the “degree”. Below are different degrees of hearing loss and how your baby may respond.

1. Mild/Slight: The child can hear most of what is said up close and in quiet environments. Noisy environments can make hearing difficult. The child will miss parts of words and may appear to be “hearing when she/he wants to”. Hearing aids may help them understand better.
2. Moderate: The child will have difficulty hearing spoken conversation, especially in noisy environments. Children may miss half, or all spoken conversations depending on background noise. Proper use of hearing devices and intervention should help the child to hear and recognize all sounds.
3. Severe: The child may hear only loud voices and sounds close to the ear. With early and consistent use of hearing aids, many children will be able to detect sounds such as speech. Hearing aids may not be helpful. Cochlear implants may offer the most access to sound and speech development. Children who do not use a cochlear implant will likely use vision in place of hearing to learn language.
4. Profound: The child will be more aware of sounds as feelings of vibrations. The child will likely use vision rather than hearing as the primary means for communication and learning. Hearing aids may not be useful. Cochlear implants may offer the most access to sound and speech development.