The 8 types of hearing impairment (and their characteristics)

These are the main types of hearing impairment classified according to various criteria.

Hearing problems are more common and diverse than they seem. Many people in our environment have trouble hearing well and need devices and medical interventions to achieve hearing within the normal range.

Not all hearing problems are the same. There are those who cannot hear at all, while others have a lower hearing range than most people but still hear.

There are several types of hearing impairment, and there are many criteria for classifying them.These criteria we are going to see below as well as mentioning some of the main causes behind hearing problems.

Types of hearing impairment, classified

Hearing impairment is defined as any condition in which the affected person has a reduced ability to perceive sound, which in turn is accompanied by problems in verbal communication. There are several types of hearing impairment, depending on the severity of the hearing loss and what problem has caused the person to be unable to hear well.

The severity of a hearing impairment is considered in terms of the minimum sound that the affected person can hear with his or her better ear.. The more decibels (dB), the louder the sound, and if there is a loss close to 90 dB, it is generally referred to as deafness. If there are problems hearing but hearing is below the 90 dB limit, the diagnoses range from mild hearing loss to hearing loss and deafness.

Hearing impairment itself is not a disease, but the consequence of various medical conditions that can cause hearing damage. Whether it is a transient or permanent loss, many hearing impaired people can achieve a completely normal life by using a variety of resources to improve their hearing. Among these improvements are hearing aids and cochlear implants, which are the equivalent of eyeglasses for the visually impaired.

Not being unable to hear not only affects hearing itself, but also hinders communication and language.. If the person is born with hearing problems, it will be difficult for him/her to learn his/her mother tongue, having difficulties in grammar, spelling and vocabulary, with its implications at a social level as he/she will not dare to start a conversation or be in an environment with several people talking.

There are several criteria for classifying types of hearing impairment. Being a very heterogeneous type of disability, it is not possible to establish a single classification, although it must be said that those that exist are not mutually exclusive. Basically, they can be classified according to the time of onset, severity, prognosis and location of the lesion.

According to the time of onset

Depending on when the person began to manifest hearing impairment we can speak of:

1. Congenital

The person is born with something that causes hearing problems.This may be due to a malformation of the structures found in the ear or to a malfunction at the nervous or cellular level.

The fact that it is congenital does not mean that it is detected early, although ideally it should be so in order to be able to intervene as soon as possible. In this regard, hearing impairments are divided into those that appear between birth and 3 years of age and those that appear after that age.

2. Acquired

Hearing impairment occurs throughout life and can be caused by multiple factors, such as the use of ototoxic drugs (which damage the hearing) or damage to the eardrum..

Not all acquired hearing loss is caused by external and avoidable factors, since hearing impairment often appears with age or as a consequence of a degenerative disease.

There are three types of acquired hearing loss, depending on when the problem was acquired: prenatal, caused during pregnancy; neonatal, caused during or immediately after birth; and postnatal, caused some time after birth.

Whether congenital or acquired, it is very important to see if they appeared before or after the person acquired the language.. If deafness was acquired before learning to speak, it would be a prelocutive hearing impairment, while if it appears after it is a postlocutive hearing impairment.

According to its severity

Depending on how much or how little the person can hear and how necessary it is to resort to special aids to achieve adequate hearing, there are three main types of hearing impairment.

3. Cophosis

Cophosis is a hearing condition in which the person cannot hear anything at all.. Some consider it a synonym of profound deafness although in this case the person can hear sounds at very high volume (90 dB).

4. Deafness

Deafness itself is a hearing impairment in which the person does not hear sounds unless the person does not hear sounds at less than 75 dB, and it is particularly severe if the person cannot hear sounds below 90 dB..

The person is deaf, but it is not a profound deafness as severe as cophosis because in this case the affected person can hear sounds if they are amplified by means of special devices.

5. Hearing loss

Hypoacusis is less serious than deafness, since the person can hear below 75 dB but not the full range of normal hearing..

In order to diagnose any of the three hearing conditions mentioned above, it is necessary to perform an audiometry, which can give the following results:

• Normal hearing: very low sounds can be heard, at or below 20 dB.
• Mild hearing loss: the lowest perceptible sound is between 20 and 40 dB.
• Medium hearing loss: sounds from 40-70 dB are detected (hypoacusis).
• Severe hearing loss: sounds are only heard from 70-90 dB (deafness).
• Profound hearing loss: hears above 90 dB (profound deafness) or does not hear at all (cophosis).

The hearing impairment does not necessarily affect both ears at the same time.. Hearing impairment may be unilateral or bilateral, i.e. one ear may be damaged and the other healthy, or both ears may have problems picking up and sending sounds to the brain. If one ear is healthy, it can be used to compensate for the situation and allow the person to live a relatively normal life without requiring too many hearing aids, although it will be difficult to detect where the sound is coming from.

Depending on the location of the lesion

Some cases of deafness are caused by a lesion which hinders the perception of sounds and their interpretation at the cortical level. Depending on the location of this lesion, we can speak of the following types of deafness.

6. Conduction deafness

The problem is either in the outer ear or in the middle ear. These have the best prognosis, since they are relatively easy to treat.. Surgical intervention may be required, such as inserting an artificial eardrum, or even a simple cleaning of the ear canal, removing an earwax plug that is affecting the patient's hearing.

7. Sensorineural deafness

Sensorineural deafness is complicated to treat since the lesion is located in deeper and more delicate places. The damage may be in the inner ear, the auditory nerve, or even in the auditory cortex, i.e. the place in the brain where the patient's hearing is affected.that is, the place in the brain where acoustic stimuli are interpreted.

8. Mixed

Hearing impairment is due to a problem in the outer and/or middle ear along with a problem at a more internal level, in the inner ear or acoustic nerve.

Prognosis

As mentioned above, hearing impairment itself is not a disease, but the consequence of a health problem that has among its symptoms an alteration in the ears or damage to the auditory nerve. Depending on what causes it and whether it can be solved, this hearing impairment may be permanent or temporary.

If it is permanent, hearing cannot be restored without the use of special aids, and may even become worse over the years, becoming more and more impaired. over the years, turning an initial hearing impairment into a cochlear hearing loss after some time. On the other hand, if the hearing impairment is transient, it can be cured by eliminating the cause or curing the disease or injury that induced it, although there may be sequelae in the form of a very mild hearing loss.

Common causes

There may be many causes behind a hearing impairment, with some being more common than others. These causes vary greatly according to the age of the affected person, and may also make the diagnosis more or less serious. Deafness in childhood is not the same as deafness in adulthood or old age, and the degree to which it can be treated and corrected is also different..

Causes in children

Deafness in children can have congenital causes. Many hearing impairments in childhood are associated with specific syndromes, with as many as 400 medical conditions currently known in which hearing impairment is associated. more than 400 medical conditions in which there is hearing loss or non-disabling hearing impairment.. Some examples are Waardenburg syndrome, with partial albinism and deafness; Usher syndrome, with hearing loss and visual problems; and Alport syndrome, with deafness and renal dysfunction.

Congenital deafness is due to the inheritance of a gene that has the syndrome or disease that causes hearing impairment. In most of these cases, the problem is usually at the level of the cochlea, that is, in the inner ear, although there are also congenital deafness cases where the damage is more external, such as a damaged ear canal or malformations in the ear.

Some children are born with hearing impairment but not caused by genetic problems, but rather by perinatal alterations.. Prematurity, low birth weight, infections that the mother may have had during pregnancy and intoxication with ototoxic substances may cause deafness in the newborn. Hearing impairment will be evident from birth and will be evident by the time the child reaches 3 years of age, by which time he or she should be able to speak but has not yet learned to hear well.

There may also be events that worsen the hearing health of the newborn in the first years of life. Their hearing is very vulnerable to external elements that can damage it, such as viral diseases like meningitis, measles or mumps, which can cause hearing problems. They are also sensitive to ototoxic drugs, trauma, the introduction of foreign bodies into the ear canal (e.g. swabs) and the appearance of ear plugs.

Causes in adults

In the case of young adults it is common to find cases of hearing loss from acoustic trauma due to exposure to sounds above 100 dB, such as discotheque loudspeakers or drills without the use of adequate sound protection (e.g. earplugs). (e.g., earplugs). Victims of blast attacks or who have witnessed the detonation of firearms may also have hearing damage.

Other factors that lead to hearing problems in adulthood are the use of ototoxic medications, wax plugs in the ear canal and the development of tumors in the auditory nerve, such as acoustic nerve neurinoma. Depending on what causes it, how long the problem has been present and how early a specialist has been consulted, deafness may or may not be reversible.

Causes in old age

Deafness is usually associated with old age. As you get older, a medical condition called otosclerosis may develop.This is the fact that the articulations of the ossicles that form the inner ear become more rigid, which causes them to vibrate less when a sound hits them. Less rigidity implies worse conduction and, therefore, the person hears less. In turn, the middle ear receptors degenerate, becoming less effective and causing poorer hearing.

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