A device for amplifying sound, used by persons with defective hearing. The earliest type was the ear-trumpet - a conical apparatus collecting sound at the wide end and delivering it to the ear-drum at the small end. Modern aids are electronic, consisting of a microphone, amplifier, and earphone, usually compressed into a very small container to fit directly on to the ear. Transmission may be to the ear-drum or by bone conduction.
For the song, see Flood (album).A hearing aid is a device used to help hard-of-hearing people hear sounds better.
During the mid- to late 20th century, hearing aids that were carried in pockets were replaced by a more inconspicuous sort of model in which small zinc-air batteries were placed in the inserted unit itself.
Types of hearing aids
There are many types of hearing aids, which vary in size, power and circuitry. Among the different sizes and models are:
Body worn aids
This was the first type of hearing aid, and thanks to developments in technology they are now rarely used. Because of their large size, body worn aids are capable of large amounts of amplification and were once used for profound hearing losses. Today, they have largely been replaced by BTEs
Behind the ear aids (BTE)
BTE aids have a small case that fits behind the ear and conducts sound to the ear through an earmold that is custom made. BTEs can be used for mild to profound hearing losses and are especially useful for children because of their durability and they can easily connect to assistive listening devices such as FM systems for classroom use. These are often less visible than ITEs and some keep the ear canal more open, so listeners may still utilise their residual natural hearing (most helpful for those with normal hearing in the lower frequencies). ITE hearing aids are custom made to fit each individual's ear. Feedback, a squealing/whistling caused by sound leaking out of the aid and being amplified again, may be a problem for severe hearing losses.
In the canal (ITC), mostly in canal (MIC) and completely in the canal aids (CIC)
ITC aids are smaller, filling only the bottom half of the external ear. You usually cannot see very much of this hearing aid when you are face to face with someone.
Open-fit devices
Recently a new device has come on the market, the "Open-fit" or "Over-the-Ear" OTE Hearing Aid. There are also devices available which have an external speaker, placed inside the ear canal, and connected to the hearing system itself by a thin cable. Open-fit devices are very beneficial for High-Frequency hearing losses, and have been introduced by all major hearing aid companies.
Bone Anchored Hearing Aids (BAHA)
The BAHA is a surgically implanted system that uses bone transmission as a pathway for sound to travel to the inner ear, bypassing the external auditory canal and middle ear. Bone anchored hearing aids are however some of the most expensive of any kind of aid.
Eyeglass aids
During the late 1950s through 1970s, before in-the-ear aids became common (and in an era when thick-rimmed eyeglasses were popular), people who wore both spectacles and hearing aids frequently chose a type of hearing aid that was built into the temple pieces of the spectacles. However, the combination of glasses and hearing aids was inflexible: the range of frame styles was limited, and the user had to wear both hearing aids and glasses at once or wear neither. Today, most people who use both glasses and hearing aids simply use in-the-ear types. There still are some specialized situations where hearing aids built into the frame of eyeglasses can be useful, such as a person with hearing loss mainly in one ear: sound from a microphone on the "bad" side can be sent through the frame to the side with better hearing.
This can also be achieved by using cross or bi-cross style hearing aids, which are now wireless in sending sound from the "bad" or "worse" side to the better side. These types of hearing aids are much more frequently used than any eyeglass style. The groundbreaking innovation employed by these 'hearing glasses' is the directional sensitivity of the hearing aid. Only very recently has the technology required become small enough, in size, to be put in the frame of the glasses.While this may be a recent addition to the market, very few hearing professionals in the United States advocate or even dispense/sell this type of hearing aid.Hearing Aid Technology
Wireless
Recent hearing aids include wireless hearing aids. One hearing aid can transmit to the other side so that pressing one aid's program button simultaneously changes the other aid and both aids change background settings simultaneously. FM listening systems are now emerging with wireless receivers integrated with the use of hearing aids. The voice is transmitted wirelessly to the hearing aids reducing the effects of distance and background noise.
Directional microphones
Many hearing aids now have directional microphones, which can be a major improvement in crowded places such as restaurants and open-plan offices, because the directional microphone allows the user to focus on whoever is directly in front with reduced interference from conversations behind and to the sides. It is common for such a hearing aid to have both a directional microphone and an omnidirectional microphone and a switch that lets the user choose between hearing in all directions versus hearing only in the direction his or her head is facing. It should be noted that these hearing aid glasses are not used by most hearing professionals due to their vulnerability to damage and the difficulty that occurs when repairs have to be made.
Telecoil
Telecoils (T-coils) allow different sound sources to be directly connected to the hearing aid, improving sound quality and allowing the hearing aid wearer to easily perceive the intended signal regardless of background noise. the T-coil then sends the signal to the hearing aid circuit or processor for amplification.
DAI
DAI-direct audio input allows the hearing aid to be connected to an external audio source like a CD player or an assistive listening device (ALD).
Processing
The inside mechanisms of hearing aids vary among devices, even if they are the same style. Three types of circuitry, or electronics, are used:
Analog/Adjustable: The hearing professional (Audiometrist, Hearing Instrument Specialist, Hearing Aid Dispenser, or Audiologist) determines the volume and other specifications required for the patient's hearing aid, and then a laboratory builds the aid to meet those specifications. Analog/Programmable: The hearing professional uses a computer to program the hearing aid. The circuitry of analog/programmable hearing aids will accommodate more than one program or setting. Analog/programmable circuitry can be used in all types of hearing aids. Digital/Programmable: The hearing professional programs the hearing aid with a computer and can adjust the sound quality and response time on an individual basis. Digital hearing aids use a microphone, receiver, battery, and computer chip. Digital circuitry provides the most flexibility for the hearing professional to make adjustments for the hearing aid. Digital circuitry can be used in all types of hearing aids and is typically the most expensive. However, digital hearing aids can be specially programmed with multiple programs for quiet situations, background noise reduction, music listening, and directionality.Adjustment to Hearing Aids
For the majority of users, hearing aids will not completely restore or fix hearing loss; Two problems occur with hearing loss that cannot be assisted by hearing aids:
When the auditory cortex of the brain does not receive input/stimulation (i.e. what happens in hearing loss), this part of the brain may start to lose cells, and the ability to process sound. This is most common with more severe hearing losses, and cannot be reversed with hearing aids. Although this cell loss is worse in severe hearing loss, it is seen in all amounts of hearing loss and is caused by sensory deprivation. In this case, amplifying speech (as a hearing aid does) does not always improve speech understanding.Multiple follow-up visits are common, particularly for new hearing aid users. The most common complaint about hearing aids, especially when someone starts wearing them for the first time, is that the sound of their own voice is too loud or that it sounds like they are talking into a barrel. Most hearing aid users will adjust to the sound of their own voices within several months if the aids are worn regularly. If the problem persists, ask your dispenser or audiologist if any adjustments can be made to the hearing aid.
Hearing aid sales
Hearing aids are often advertised at widely varying prices, from $300 US to $5,000 US per hearing aid. A major factor contributing to the wide variance in price is the number and complexity of hearing aids available. Another factor in the variance of prices is the bundling of services needed to customize a hearing aid to a specific ear and hearing loss. The complexity of these devices, the amount of customization required, and the personal nature of hearing suggest the best place to buy a hearing aid is somewhere you are comfortable, from someone you trust.
Buyers of hearing aids will commonly seek the expert advice of audiologists or audiometrists. Audiologists will have specially calibrated equipment and sound proof booths to conduct comprehensive hearing tests to describe a hearing loss.
In the United States, Hearing aid dispensers (Hearing Instrument Specialists) also sell hearing aids. Hearing Instrument Specialists are professionals with at least a high school diploma and 2 years of training/apprenticeship in hearing aid sales.
In addition to the results of a hearing test, which describe a hearing loss, a recommendation for a specific amplification instrument should consider a person's listening lifestyle. Many features available in hearing aids (multiple and directional microphones, noise reduction strategies, "programs", etc.) represent strategies to address specific situations. Features that are not used by the individual may increase the cost and complexity of a hearing aid.
Another consideration for determining the optimal hearing aid is physical and mental dexterity. Many hearing aids offer special features, such as different "programs".
Finally, there are also personal concerns such as cost and the visibility of the hearing aid. Hearing aids are typically not covered, or only partially covered, by most insurance plans in the United States. The visibility of a hearing aid to others is important to some people. There is often a stigma associated with large visible amplification instruments, such as BTEs, so many people prefer hearing aid that are discreet.
The FCC recommends a 30-day trial period with hearing aids. Not all audiologists and dispensors offer this, even though most hearing aid companies offer them a 30-60 day trial period. During the trial period, a consumer may need to return for adjustments several times before the hearing aids are best set for their listening environment. If the hearing aid is returned, most facilities charge a restocking fee to pay for the audiologist or dispensor's time.
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