Hypoacusis: Decreased Hearing and Loss of Hearing

congenita), while others may develop it gradually with advancing age (presbycusis) or as a consequence of illness or physical trauma. Heredity and chronic exposure to loud noises are believed to be the main contributing factors to hearing loss over time. Other factors, such as the presence of a wax plug or foreign bodies in the ear canal, can prevent normal perception of sounds.

Diagnosis allows you to determine the severity of the hearing problem. Your doctor or specialist may recommend a number of measures to improve conductive problems, but in some cases it is impossible to reverse or prevent hearing loss.

transforms these sound waves into auditory nerve impulses, which are transmitted to the brain. Anatomically, the ear in humans is divided into three main areas:

• Outer ear: formed by the auricle and the ear canal. Thanks to its structure, it allows sound waves to be channeled towards the eardrum membrane, which provides the surface for sound collection and vibrates in response.
• Middle ear: transmits the vibratory mechanical energy of sound. It consists of a system of three auditory ossicles (hammer, anvil and stirrup), which amplifies and transfers the vibrations coming from the eardrum to the oval (or round) window, an opening in the bony wall of the middle ear cavity.
• Inner ear: besides controlling the balance, it is responsible for the transduction of the mechanical vibratory energy of sound into nerve impulses. The auditory ossicles amplify the vibrations and conduct the stimulus to the inner ear, through the fluid contained in the cochlea (endolymph), a snail-shaped structure located in the inner ear. Hairy (or ciliated) cells located in the cochlea move in response to oscillations and help transduce the sound wave into an electrical signal that is transmitted from the acoustic-state nerve to the brain.

All conditions in the middle ear that block the normal transfer of vibrations from the tympanic membrane to the oval window cause conduction (peripheral) deafness. Any obstacle outside the ear canal, such as a plug of earwax or water, can cause a temporary hearing loss. Scarring and perforation of the eardrum membrane or the immobilization of one or more auditory ossicles are among the most serious examples of hearing loss.

When the problem occurs at the level of the cochlea or along the acoustic pathway, nervous (central) deafness occurs. In this case the vibrations continue to arrive at the oval window, but the receptors do not respond or emit responses that do not reach the destination, ie the brain. Certain drugs are able to penetrate the endolymph and can destroy the receptors. Bacterial infections can also damage hair cells or nerve structures.

. Conductive hearing loss usually results in a reduction in sound level and sounds are perceived as faint.

Sensorineural hearing loss: Reduces the ability to hear faint sounds and occurs when hair cells in the inner ear (cochlea) or nerve pathways are damaged. Sensorineural hearing loss is the most common type of permanent hearing loss and needs especially as a consequence of the natural aging process or trauma;

Mixed hearing loss: Sometimes, a "conductive hearing loss occurs at the same time as a" sensorineural hearing loss. In other words, there may be damage in the middle or outer ear and the inner ear (cochlea) or the auditory nerve.

, they do not necessarily cause hearing loss.

• Mild hearing loss (acoustic deficit between 25 and 39 dB). Mild hearing loss can sometimes make it difficult to follow a speech, especially in noisy situations.
• Moderate hearing loss (acoustic deficit between 40 and 69 dB). In this case, the patient may have difficulty following the speech without using a hearing aid.
• Severe hearing loss (acoustic deficit between 70 and 89 dB). People who are severely deaf usually need to use some form of alternative communication, such as lip reading or sign language, even with the use of a hearing aid.
• Deafness or profound hearing loss (hearing loss> 90 dB). People who are completely unable to hear a sound can often benefit from a cochlear implant.

To provide an idea, it may be helpful to compare hearing loss levels with some familiar sounds:

Loudness of some common noises Decibel Source of noise Safety range 20 Clock ticking 30 Whisper 50-60 Normal conversation 80 Sound of an alarm clock Risk range 85-90 Hairdryer 100 Snowmobile, rock concert 110 Firing hammer Headband of injuries 120 Ambulance siren 140 (pain threshold) Jet 180 Rocket launch

Sounds approaching 100 dB can cause hearing damage.

. Symptoms of hearing loss can vary depending on the cause. Hearing loss can develop gradually over time, particularly from factors associated with noise exposure and age. Hearing loss can occur more quickly if it is related to the presence of excess earwax, infections or diseases in the middle ear.
Signs and symptoms associated with hearing loss can include:

• Some sounds seem muffled;
• Difficulty understanding words and following conversations, especially when there is background noise or when you are in a crowd of people;
• Others are often asked to speak more slowly, clearly and loudly;
• There is a need to turn up the volume on the television or radio.

Other symptoms include:

• Vertigo or a feeling of lack of balance (more common in Ménière's syndrome and acoustic neuroma);
• Pressure in the ear (due to a change in the fluid behind the eardrum);
• Ringing in the ears (tinnitus).

within the first few weeks of birth, as part of the Newborn Hearing Screening (NHSP) program.
However, some signs may suggest considering "further hearing evaluation", for example if you notice that your child:

• He is not afraid of loud noises;
• Within four months of life, it does not spontaneously turn to a sound source;
• He shows a delay in "learning to pronounce the first words or these are not clear when he expresses himself.

and perforation of an eardrum.