Generality
Hearing aids, or hearing aids, are small electronic devices that - applied behind or inside the ear - guarantee people with hearing impaired neurons to recover part of their hearing, clearly improving their quality of life.
To operate in this way, a typical hearing aid uses three elements: a microphone, for capturing sound vibrations; an amplifier, to increase the volume of sound vibrations otherwise inaudible; finally, a loudspeaker, to channel the amplified sound vibrations to the internal structures of the ear.
There are two main types of hearing aids: behind-the-ear hearing aids, which the wearer wears behind the ear, and endo-auricular (or intra-ear) hearing aids, which the wearer wears inside the ear. Both these types include various subtypes, which may be more or less suitable for certain categories of patients.
To work best, a hearing aid must be adjusted based on the hearing impairment of the wearer; the correct adjustment of the hearing aids is very often the result of several attempts.
Short revision of the inner ear and the cochlea
The inner ear essentially comprises two hollow structures: the cochlea, which is the organ of hearing, and the vestibular system (or vestibular apparatus ), which is the organ of balance.
Each of these organs is connected to the brain by means of a nerve: the cochlea via the cochlear nerve, while the vestibular system via the vestibular nerve .
A fluid called endolymph circulates inside the cochlea and the vestibular system. Rich in potassium, endolymph is essential for auditory perception and balance, as it plays a decisive role in the transmission of nerve signals / impulses from the inner ear to the brain.
SCREW
Morphologically similar to a snail, the cochlea is in fact the center of conversion of sounds into nerve signals / impulses. For the conversion process, it uses particular hair cells, dispersed in the endolymph; these hair cells are called Corti organ .
Once the conversion process has taken place, the organ of Corti and the endolymph interact with the cochlear nerve, which at this point transmits the newly formed nerve signals / impulses to the brain, for their final processing.
What are hearing aids?
Hearing aids are small electronic devices that, mounted behind or inside the ear, allow people with reduced hearing ability to hear better, even in particularly noisy environments.
Also known as hearing aids, hearing aids are actually sound amplifiers .
IS AN ACOUSTIC DEVICE A COCHLEAR IMPLANT?
It is a mistake to confuse hearing aids with cochlear implants .
In fact, while a hearing aid is a sound amplifier, a cochlear implant is a sort of artificial cochlea, as it picks up sounds and transforms them - just like the original hearing organ - into nerve signals / impulses, which it subsequently sends to the brain through the cochlear nerve.
Indications
The use of hearing aids is indicated, in most cases, for people with acoustic deficits or deafness of the neuro-sensory type .
Acoustic deficits and neuro-sensory deafness are hearing disorders, which appear as a result of cochlea problems (eg, degeneration of the organ of Corti, reduction in the number of hair cells in the cochlea etc.) and / or cochlear nerve.
Acoustic deficits and neuro-sensory deafness can be more or less serious, depending on the causes.
Most common causes of acoustic deficits and neuro-sensory deafness:
- Diseases such as, for example, Ménière's syndrome.
- Acoustic traumas, resulting for example in the explosion of a firecracker or a tire near the ears;
- Presbycusis . It is the reduction / loss of hearing ability related to aging.
Mono or Bilateral use
The indication for the use of a hearing aid could be an ear ( unilateral indication) or both ( bilateral indication), depending on whether the hearing impairment affects one or both ears.
Components and operation
A generic hearing aid has three main components, which are: a microphone, an amplifier and a speaker .
The microphone is used to pick up the sounds (or sound vibrations) circulating in the environment and transmit them to the amplifier.
The amplifier - as the name suggests - amplifies the sounds received by the microphone (similar to the positive volume control on a television) and transports them to the speaker.
Finally, the loudspeaker has the task of channeling the amplified sounds into the ear, thus favoring the auditory perception of the hearing aid wearer.
HOW DOES SOUND AMPLIFICATION WORK?
The functioning of hearing aids is based on the idea that sound amplification allows a Corti organ not perfectly healthy to recognize / identify sounds (which otherwise would not be able to perceive).
Hearing aids are not so much devices that restore normal hearing, but are rather devices that compensate for a hearing deficit. Therefore, it is wrong to think that their use represents a definitive solution to deafness or a decline in sound perception.
SETTING OF AMPLIFICATION
Modern hearing aids offer the possibility of adjusting the sound amplification to different levels, depending on the needs of the wearer.
In exemplary terms, this means that an individual with a slight hearing impairment will adjust sound amplification to a lower level than an individual with a severe hearing impairment.
Having said this, the adjustment of the hearing aids is not a simple and immediate operation; in fact, it is often necessary to make a few attempts, before finding an amplification volume that meets the needs of the wearer.
In individuals who need an ear hearing aid, a double adjustment of sound amplification is required, one for each device, as each ear will have a specific hearing impairment, different from the other.
BATTERY POWER SUPPLY
Generally, current hearing aids work thanks to a small battery, very easy to replace once unloaded.
Types
Currently, there are two main types of hearing aids: the hearing aids that the patient wears behind the outer ear, specifically called behind-the-ear hearing aids, and the hearing aids that the patient wears inside the outer ear, more commonly called hearing aids endo-auricular (or intra- ear hearing aids ).
RETROAURICULAR ACOUSTIC EQUIPMENT
Behind-the-ear hearing aids are characterized by a sort of shell to be placed behind the outer ear, in which all or almost all the electronic components necessary for improving hearing ability reside.
Currently, 3 sub-types of behind-the-ear hearing aids are available:
- Standard BTE or BTE .
Features: all the electronic components of the hearing aids in question reside in the shell.
The transmission of amplified sounds inside the ear takes place thanks to a small tube, which, starting from the upper part of the shell, moves up to the opening of the external auditory canal and finds anchorage there, through a small earpiece.
BTEs are an excellent solution for those with moderate or severe hearing impairment.
- The open ear earbuds .
Features: they are very similar to standard hearing aids, even with regard to effectiveness. The only difference lies in the earpiece, which is even smaller, so it takes up less space at the level of the external ear canal.
- Behind-the-ear with speaker in the channel or RIC .
Features: microphone and sound amplifier housed in the shell.
The loudspeaker, instead, takes place in the external auditory canal, very close to the eardrum.
Connecting the shell to the loudspeaker are very fine cables that run inside a special connection tube.
From the point of view of size, the RIC shell is slightly smaller than the BTE shell; after all, one of the three main components takes place in an external element of the device.
RICs are valid solutions both in case of moderate hearing impairment and in case of severe hearing impairment.
ENDOAURICULAR ACOUSTIC EQUIPMENT
In-the-ear hearing aids are custom-made devices, whose constituent shell fits perfectly into the external auditory canal and contains all three main electronic components of a generic hearing aid.
In addition to being an excellent solution to hearing impairment, endo-auricular hearing aids also have an aesthetic advantage, as they can be positioned in little or no visible points with the naked eye.
At present, 3 subtypes of in-the-ear hearing aids are available:
- Standard or ITE earphones .
Characteristics: the shell that encloses the electronic components is tailor-made for the patient, to fit perfectly into the auricle of the ear.
The conch of the auricle is the concave region, in which the opening of the external auditory canal takes place.
Tailor-made construction creates a personal device that hardly moves once applied. This represents a real comfort for patients who have a fairly active life.
Minimally visible, ITEs are a good solution for both mild hearing defects and moderate hearing defects.
- The pretimpanic endoauricular or CIC .
Characteristics: the CIC consist of a shell that contains all the fundamental electronic components and is specifically designed to fit inside the external auditory canal, in the first section.
Therefore, compared to ITE, CICs are even more discreet, in the sense that they are even less visible.
Their extraction, should it be necessary to change the batteries or one of the devices were damaged, is simple, as a small transparent extraction cord is tied to the shell.
CICs can compensate for mild and moderate hearing difficulties.
- Invisible in-the-ear in the canal or IIC .
Features: the shell is made specifically for its housing in the depths of the external auditory canal.
They are highly personal and, compared to the previous two sub-types, they go unnoticed even to a particularly careful vision.
They are an excellent solution for almost all degrees of hearing impairment; in fact, in the presence of severe hearing difficulties, they offer few advantages.
Figure: example of an endo-auricular hearing aid.
Table. Summary of the advantages and disadvantages of the two different types of hearing aids.
| Type of hearing aid | Advantages | Disadvantages |
Behind-the-ear hearing aids |
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|
In-the-ear hearing aids |
|
|
CHOICE OF THE TYPE OF ACOUSTIC DEVICE
The choice of the hearing aid - from the type to the subtype - is the responsibility of the hearing care technician, to whom the future bearer of the device relies. This choice depends, first of all, on the severity of the hearing impairment and, secondly, on the lifestyle of those who wear it.
Here are some examples to understand:
- People with severe hearing impairment need powerful hearing aids, so they are behind the ear. Conversely, people with mild or moderate hearing impairment can also safely wear endo-auricular hearing aids.
In these situations, an active lifestyle or a tendency to have a sedentary lifestyle have a relative relevance, as the primary objective is to re-establish a certain hearing ability.
- In the presence of mild or moderate hearing impairment, consideration of the patient's lifestyle is important. For active people (ex: young people), the best choice is the endo-ear type hearing aid, as the latter allows more freedom of movement. Conversely, for people who are sedentary or less able to handle electronic devices (eg: the elderly), the best choice is generally the behind-the-ear type hearing aid, as it is easy to remove and manage.
Who is an audiologist?
A hearing care professional is a healthcare professional who specializes in the prevention, correction and rehabilitation of auditory function deficiencies.
To become a hearing aid technician, you must obtain a degree in hearing aid techniques.
Installation
The installation of hearing aids is a simple operation, which anyone can learn easily enough by observing a specific user manual or the advice of a hearing care professional. The convenience of learning how to install a hearing aid lies in the fact that the wearer of the aforementioned device becomes completely autonomous, unless mechanical failures appear.
Generally, from when the use of a hearing aid begins, a check of the instrument is provided, with your hearing care professional, after about 12 weeks . On this occasion, the bearer can address any doubts or concerns regarding the operation of the device.
Clearly, if the hearing aid develops any problems before the aforementioned 12 weeks have elapsed, the wearer should contact his hearing care professional and fix an earlier appointment with him.
Management and duration
Proper management of hearing aids ensures their long life and proper functioning over time.
The list of tips for good hearing aid management includes:
- Keep hearing aids away from sources of heat and particularly wet areas;
- Provide for the periodic cleaning of hearing aids, according to the instructions provided by the experts;
- While wearing hearing aids, avoid using hairspray or other hair care products;
- Turn off your hearing aids when you don't need to use them;
- Have the batteries replaced immediately when they are discharged;
- Always have spare batteries available;
- Keep your hearing aids away from children and animals.
Risks and complications
Noted that hearing aids are safe for the wearer's health, wearers could be victims of some inconveniences, including:
- Feeling uneasy . In the initial moments following the very first installation, the hearing aids could be annoying. In these situations, it is only a matter of time: in a few days, in fact, the bearer gets used to the presence of the device.
- Too high perception of one's voice . It may depend on a lack of habit of using the hearing aid or it may derive from an incorrect adjustment of the sound amplification. In the second case, the device should be re-adjusted.
- Perception of a whistling noise . It can be linked to an accumulation of wax or to an incorrect realization of the device.
- Perception of background noise . It is due to the malfunction of the appliance, which does not discern useful sounds and sounds that are not useful to the wearer.
- Perception of a buzz, in the presence of one or more mobile phones . Some mobile phones interfere with the operation of hearing aids. In these situations, it is good to understand which phones represent an interference and which are not.
The technology is doing a giant leap, but there are still some problems to be solved.
WHAT TO DO IN CASE OF MECHANICAL FAILURES?
If the hearing aids give the clear impression of being the subject of a mechanical failure (eg: the presence of hum or background noise, etc.), it is advisable to contact or go immediately to your hearing care professional and explain the problem to him, in order to solve it in as soon as possible.
Results
Modern hearing aids are very effective devices in reducing the impact that a certain range of hearing loss can have on an individual's quality of life (NB: extremely severe deafness remains incurable even with the most technological of hearing aids).
Many of those who wear hearing aids claim to be satisfied with the device in use because the device allowed them to:
- To return to hear the sounds of everyday life quite distinctly (eg: a doorbell, telephone, etc.);
- Come back to hear what people are saying nearby, then actively participate in conversations, discussions, etc.
- Recover the ability to follow an event on television and listen to music.
- Come back to feel the sounds, even in the presence of confusion.
THE SEARCH CONTINUES ...
Despite the good results provided by current hearing aids, the search for even more effective devices continues.
It is not excluded, therefore, that in the near future the discovery of new technologies offers the possibility of developing hearing aids capable of compensating for hearing deficits, which for the moment are incurable.
