A hearing aid is a small electronic device that you wear in or behind your ear. It makes some sounds louder so that a person with hearing loss can listen, communicate, and participate more fully in daily activities. A hearing aid can help people hear more in both quiet and noisy situations. However, only about one out of five people who would benefit from a hearing aid actually uses one. A hearing aid has three basic parts: a microphone, amplifier, and speaker. The hearing aid receives sound through a microphone, which converts the sound waves to electrical signals and sends them to an amplifier. The amplifier increases the power of the signals and then sends them to the ear through a speaker.
When you listen to something, whether it is a car alarm or a dog barking, the sound travels through the opening of your outer ear and causes your eardrum to vibrate. Three small bones in your middle ear carry this vibration to the cochlea,the shell-shaped structure in your inner ear. The vibration stimulates hair cells, which create an electrical current in the auditory nerve. This current transmits the sound via nerve impulses to your brain, where it is processed into noise, like the sound of a car alarm or that of a dog barking.Picture provided by: http://static.howstuffworks.com/gif/hearing-2.jpg
Telecoils (T-coils), sometimes referred to as "Telephone Coils", allow audio sources to be directly connected to a hearing aid, which is intended to help the wearer filter out background noise. They can be used with telephones, FM systems (with neck loops), and induction loop systems (also called "hearing loops") that transmit sound to hearing aids from public address systems and TVs. In the UK and the Nordic countries, hearing loops are widely used in churches, shops, railway stations, and other public places. In the U.S.A., telecoils and hearing loops are gradually becoming more common.
Conductive hearing loss occurs when sound doesn't move as it should through the eardrum, ear canal or the three bones of the inner ear. It can be caused by earwax, a punctured eardrum, fluid in the ear, a genetic defect or an infection. The result is a sensation as though your ears are plugged. Conductive hearing loss can be treated with surgery. Sensorineural hearing loss involves damage to the cochlea. It's the most common type, affecting about 90 percent of people with hearing loss. Sensorineural hearing loss can be a byproduct of aging, or it can occur due to infections, genes,head trauma, exposure to loud noises or fluid buildup in the inner ear. This is the type of hearing loss that a hearing aid can help.
Hearing aids work differently depending on the electronics used. The two main types of electronics are analog and digital. Analogaids convert sound waves into electrical signals, which are amplified. Analog/adjustable hearing aids are custom built to meet the needs of each user. The aid is programmed by the manufacturer according to the specifications recommended by your audiologist. Analog/programmable hearing aids have more than one program or setting. An audiologist can program the aid using a computer, and the user can change the program for different listening environments—from a small, quiet room to a crowded restaurant to large, open areas, such as a theater or stadium. Analog/programmable circuitry can be used in all types of hearing aids. Analog aids usually are less expensive than digital aids. Digitalaids convert sound waves into numerical codes, similar to the binary code of a computer, before amplifying them. Because the code also includes information about a sound’s pitch or loudness, the aid can be specially programmed to amplify some frequencies more than others. Digital circuitry gives an audiologist more flexibility in adjusting the aid to a user’s needs and to certain listening environments. These aids also can be programmed to focus on sounds coming from a specific direction. Digital circuitry can be used in all types of hearing aids.
Behind the Ear (BTE) hearing aids consist of a hard plastic case worn behind the ear and connected to a plastic earmold that fits inside the outer ear. The electronic parts are held in the case behind the ear. Sound travels from the hearing aid through the earmold and into the ear. BTE aids are used by people of all ages for mild to profound hearing loss. A new kind of BTE aid is an open-fit hearing aid. Small, open-fit aids fit behind the ear completely, with only a narrow tube inserted into the ear canal, enabling the canal to remain open. For this reason, open-fit hearing aids may be a good choice for people who experience a buildup of earwax, since this type of aid is less likely to be damaged by such substances. In addition, some people may prefer the open-fit hearing aid because their perception of their voice does not sound “plugged up.” Picture provided by: http://audibel.com/images/products/styles_bte.jpg
In-the-Ear (ITE) hearing aids fit completely inside the outer ear and are used for mild to severe hearing loss. The case holding the electronic components is made of hard plastic. Some ITE aids may have certain added features installed, such as a telecoil. A telecoil is a small magnetic coil that allows users to receive sound through the circuitry of the hearing aid, rather than through its microphone. This makes it easier to hear conversations over the telephone. A telecoil also helps people hear in public facilities that have installed special sound systems, called induction loop systems. Induction loop systems can be found in many churches, schools, airports, and auditoriums. ITE aids usually are not worn by young children because the casings need to be replaced often as the ear grows. Picture provided by: http://audibel.com/images/products/styles_ite.jpg
The ITC hearing aid works only for mild to moderate hearing loss. It is customized to fit the size and shape of the person's ear canal. Although this hearing aid is inconspicuous, its small size makes it difficult to adjust and change the battery. Some ITC hearing aids come with a remote control to make changing the settings easier. Also, users sometimes experience feedback noise with this type of hearing aid because the microphone and receiver sit close together. They usually are not recommended for young children or for people with severe to profound hearing loss because their reduced size limits their power and volume.Picture provided by: http://audibel.com/images/products/styles_itc.jpg
This hearing aid is also appropriate for mild to moderate hearing loss, and it's even smaller than the ITC hearing aid. In fact, it's so small that a user must pull on a small wire to remove it from his ear. Because it fits completely in the ear canal, the CIC hearing aid is barely visible. Again, though, its small size makes it difficult to adjust and use added features. It's also more expensive than larger hearing aids.Picture provided by: http://audibel.com/images/products/styles_cic.jpg
Traditional hearing aids work well for people with varying degrees of hearing loss, but they can't restore sound to people who are profoundly deaf. Cochlear implants work better in people with more severe ear damage because they bypass the damaged parts of the ear and send the sound information ,as electrical signals,directly to the auditory nerve. Cochlear implants can be used alone or with traditional hearing aids in people who have mild hearing loss at some frequencies but more severe hearing loss at other frequencies. The cochlear implant is made up of two main systems: an external system and an internal system. The external system is composed of three parts: a sound processor, a microphone and a transmitter. The internal system features a receiver and an electrode array. The microphone, which is attached to the sound processor, captures sound and sends it to the sound processor, a small device that can be inconspicuously clipped over the outer ear. The transmitter sits behind the sound processor and connects to the scalp directly outside where the internal receiver is implanted under the skin. The transmitter is fitted with a magnet that holds it onto the internal receiver. (Instead of being fastened to the scalp and ear, the external system can also be carried in a shirt pocket or hip pouch.) The receiver, which is about the size of a quarter, is implanted under the skin in the bone behind the ear. And the electrode array is a wire that runs from the implant into the cochlea.The microphone picks up sound and sends it to the sound processor, which translates sound into digital information. It sends this digital information to the implanted receiver, which changes the digital information into electrical signals and sends these signals to the electrode array. The electrode array sends these signals to the auditory nerve, which then passes along the signals to the brain.
New bone-anchored (baha) hearing aids bypass the normal hearing process to help people with severe sensorineural, conductive or mixed hearing loss who can't be helped by regular hearing aids. Instead of merely amplifying sound, these surgically implanted devices attach to the bones in the middle ear. Bypassing the auditory canal and middle ear, baha hearing aids create vibrations in the skull and transmit those vibrations directly to the cochlea through a process called direct bone conduction. Picture provided by: http://www.countrydoctor.co.uk/education/educat17.gif
At the turn of the 21st century, computer technology made hearing aids smaller and even more precise, with settings to accommodate virtually every type of listening environment. The newest generation of hearing aids can continually adjust themselves to improve sound quality and reduce background noise. Hearing aids available today are smaller and more powerful than ever, and researchers are aiming for even higher sound quality in the future. They're looking for ways to better amplify the sound signal and reduce feedback using the latest computer technology. Many innovations are in the works to further refine this essential aid for its recipients. Every moment, we are closer to achieving the gift of hearing to those whom do without.
Hearing Aids<br />A Closer Look<br />
What is a hearing aid?<br />Small electronic device<br />Quiet and noisy situations<br />1 out of 5 who needs, actually uses<br />Three Basic Parts<br />Microphone<br />Amplifier<br />Speaker<br />
How does “hearing” work?<br />Sound travels through outeer ear<br />Eardrum vibrates<br />Three smalls bones carry sound to cochlea<br />Vibration stimulates hair cells<br />Creates electrical current to auditory nerve<br />Transmits to brain<br />
Hearing aid technology<br />Telecoil<br />Connect directly to hearing aid<br />Filters background noise<br />Used with telephones, FM systems, and induction loop systems<br />Directional Microphones<br />Amplify sounds more from front<br />Better signal to noise radio<br />Improves speech understanding in noise<br />
What causes hearing loss?<br />Two types of hearing loss:<br />Conductive hearing loss<br />Sound obstructed through the ear<br />Treatable with surgery<br />Sensorineuralhearing loss<br />Damage to the cochlea<br />Most common type<br />Type helped by hearing aid<br />
How do hearing aids work?<br />2 types of hearing aids<br />Analog<br />Converts sound waves into electrical signals<br />Custom built for each user<br />Less expensive<br />Digital<br />Converts sound waves into numerical codes<br />Similar to binary code<br />More flexibility in adjustment<br />
What type of hearing aids are there?<br />BTE (Behind-the-Ear)<br />Fits behind pinna(ear)<br />Consists of case, earmold, & tube<br />Sound routed from case to earmold<br />Mini BTE<br />
What type of hearing aids are there?(continued)<br />ITE (In-the-Ear)<br />Mild to severe hearing loss<br />Completely inside outer ear<br />Not recommended for children<br />Capable of added features<br />telecoil<br />
What type of hearing aids are there?(continued)<br />ITC(In-the-Canal)<br />Mild to moderate hearing loss<br />Customized to recipient<br />Almost completely hidden<br />Difficult to adjust and change battery<br />
What type of hearing aids are there?(continued)<br />CIC(Completely-in-Canal)<br />Mild to moderate hearing loss<br />Smaller than ITC<br />Difficult to adjust and add features<br />More expensive<br />
Cochlear Implant<br />Designed for those who are profoundly deaf<br />Can be used alone or with traditional hearing aid<br />Two main systems:<br />External<br />Sound processer, microphone, and transmitter<br />Internal<br />Receiver and electrode array<br />
Future for hearing aids<br />BAHA(Bone Anchored Hearing Aid)<br />Bypass normal hearing system<br />Helps severe sensorineural, condutive, or mixed<br />Attach to bones in middle ear<br />Bypasses auditory canal and middle ear<br />
Conclusion<br />Hearing aids are smaller and more powerful<br />Aiming for higher sound quality in the future<br />Accommodate virtually every type of listening environment<br />Continually adjust themselves to improve sound quality and reduce feedback<br />Closer to achieving gift of hearing<br />
References<br />National Institute on Deafness and Other Communication Disorders, . (2010, March 04). Hearing aids. Retrieved from http://www.nidcd.nih.gov/health/hearing/h earingaid.asp <br />Anne Eisenberg, . (2006, September 24). <br />The Hearing aid as fashion statement. The New York Times<br />LastPaulDybala, . (2006). Hearing aid or headset?. Audiology Online, Retrieved from http://www.audiologyonline.com/articles/article_detail.asp?article_id=1542 <br />