Citizendia
Your Ad Here

Behind the ear aid
Behind the ear aid
For the song, see Flood (They Might Be Giants album). Flood is the third studio album by They Might Be Giants, and their first with a major label Elektra Records.

A hearing aid is an electroacoustic body-worn apparatus which typically fits in or behind the wearer's ear, and is designed to amplify and modulate sounds for the wearer. In Telecommunications, modulation is the process of varying a periodic Waveform, i Earlier devices, known as an "ear trumpet" or "ear horn"[1][2], were passive funnel-like amplification cones designed to gather sound energy and direct it into the ear canal. A horn is a tapered sound guide designed to provide an acoustic impedance match between a sound source and free air Passivity is a property of engineering systems most commonly used in electronic engineering and control systems Generally an amplifier or simply amp, is any device that changes usually increases the amplitude of a signal. Similar devices include the bone anchored hearing aid, and cochlear implant. A Bone-Anchored Hearing Aid is a type of Hearing aid based on Bone conduction. A cochlear implant (CI is a surgically implanted electronic device that provides a sense of Sound to a person who is profoundly deaf or severely hard of hearing

Contents

Types of hearing aids

There are many types of hearing aids (also known as hearing instruments), which vary in size, power and circuitry. Electric power is defined as the rate at which Electrical energy is transferred by an Electric circuit. An electronic circuit is a closed path formed by the interconnection of Electronic components through which an Electric current can flow Among the different sizes and models are:

NIH illustration of different hearing aid types.
NIH illustration of different hearing aid types.

Body worn aids

This was the first type of hearing aid invented by Harvey Fletcher while working at Bell Laboratories. Harvey Fletcher ( September 11, 1884 – July 23, 1981) was an American Physicist. Bell Laboratories (also known as Bell Labs and formerly known as AT&T Bell Laboratories and Bell Telephone Laboratories) is the Research organization Thanks to developments in technology they are now rarely used. These aids consist of a case containing the components of amplification and an ear mold connected to the case by a cord. Generally an amplifier or simply amp, is any device that changes usually increases the amplitude of a signal. The case is about the size of a pack of playing cards and is worn in the pocket or on a belt. A playing card is a piece of specially prepared heavy paper thin card or thin plastic figured with distinguishing motifs and used as one of a set for playing Card games Because of their large size, body worn aids are capable of large amounts of amplification and were once used for profound hearing losses. Today, body aids have largely been replaced by Behind-The-Ear (BTE) instruments.

Behind the ear aids (BTE)

BTE aids have a small plastic case that fits behind the pinna (ear) and provides sound to the ear via air conduction of sound through a small length of tubing, or electrically with a wire and miniature speaker placed in the ear canal. The pinna ( Latin for Feather) is the visible part of the Ear that resides outside of the head (this may also be referred to as the auricle or The ear canal ( external auditory meatus, external acoustic meatus) is a tube running from the Outer ear to the Middle ear. The delivery of sound to the ear is usually through an earmold that is custom made, or other pliable fixture that contours to the individuals ear. An earmold (ear mold british ear mould or earmould is a device worn inserted into the Ear for sound conduction or ear protection BTEs can be used for mild to profound hearing losses and are especially useful for children because of their durability and ability to connect to assistive listening devices such as classroom FM systems. Their colors range from very inconspicuous skin tones to bright colors and optional decorations. Recent innovations in BTEs include miniature "invisible" BTEs with thin hair-like sound tubes (see open-fit devices below). These are often less visible than In-The-Ear aids (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). Frequency is a measure of the number of occurrences of a repeating event per unit Time. Ideal for high frequency losses, these miniature versions are generally used for mild to moderate hearing loss.

In the ear aids (ITE)

These devices fit in the outer ear bowl (called the concha); they are sometimes visible when standing face to face with someone. ITE hearing aids are custom made to fit each individual's ear. They can be used in mild to some severe hearing losses. Feedback, a squealing/whistling caused by sound of leaking air and being amplified again, may be a problem for severe hearing losses. Audio Feedback (also known as the Larsen effect after the Danish scientist Søren Larsen who first discovered its principles is a special kind of Feedback Some modern circuits are able to provide feedback regulation or cancellation to assist with this. Traditionally, ITEs have not been recommended for young children because their fit could not be as easily modified as the earmold for a BTE, and thus the aid had to be replaced frequently as the child grew. However, there are new ITEs made from a silicone type material that mitigates the need for costly replacements. Silicones are largely inert compounds with a wide variety of forms and uses

Receiver In the ear aids (RITE)

At a first glance, these devices are similar to the BTE aid. There is however one crucial difference: The speaker ('receiver') of the hearing aid is placed inside the ear canal of the user and thin electrical wires replaces the acoustic tube of the BTE aid. There are some advantages with this approach: Firstly, the sound of the hearing aid is arguably smoother than that of a traditional BTE hearing aid. With a traditional BTE hearing aid, the amplified signal is emitted by the speaker (receiver) which is located within the body of the hearing aid (behind the ear). The amplified signal is then directed to the ear canal through an acoustic tube, which creates a peaky frequency response. With a RITE hearing aid, the speaker (receiver) is right in the ear canal and the amplified output of the hearing aid does not need to be pushed through an acoustic tube to get there, and is therefore free of this distortion. Secondly, RITE hearing aids can typically be made with a very small part behind-the-ear and the wire connecting the hearing aid and the speaker (receiver) is extremely inconspicuous. For the majority of people this is one of the most cosmetically acceptable hearing device types. Thirdly, RITE devices are suited to "open fit" technology (see below) so they can be fitted without plugging up the ear, offering relief from occlusion.

In the canal (ITC), mini 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. MIC and CIC aids are often not visible unless you look directly into the wearer's ear. [3][4] These aids are intended for mild to moderately-severe losses. CICs are usually not recommended for people with good low frequency hearing, as the occlusion effect is much more perceivable. [5]

Open-fit devices

"Open-fit" or "Over-the-Ear" OTE hearing aids are small behind-the-ear type devices. This type is characterized by a small plastic case behind the ear, and a very fine clear tube running into the ear canal. Inside the ear canal, a small soft silicone dome or a molded, highly vented acrylic tip holds the tube in place. VRLA stands for valve regulated lead acid and is the designation for low maintenance lead-acid batteries, also called recombinant batteries Poly(methyl methacrylate ( PMMA) or poly(methyl 2-methylpropenoate is a Thermoplastic and transparent Plastic. This design is intended to reduce the occlusion effect. The occlusion effect occurs when an object fills the outer portion of a person's ear canal and that person perceives "hollow" or "booming" echo-like sounds of their Conversely, because of the increased possibility of feedback, they are limited to moderate high frequency losses.

Bone Anchored Hearing Aids (BAHA)

The BAHA is a auditory prosthetic which can be surgically implanted. A Bone-Anchored Hearing Aid is a type of Hearing aid based on Bone conduction. In Medicine, a prosthesis (plural prostheses) is an Artificial extension that replaces a missing Body part. Surgery (from the χειρουργική cheirourgikē, via chirurgiae meaning "hand work" is a medical specialty that uses operative manual and instrumental An implant is a Medical device made to replace and act as a missing biological structure (as compared with a transplant, which indicates transplanted Biomedical The BAHA uses the skull as a pathway for sound to travel to the inner ear. The inner Ear is the bony labyrinth, a system of passages comprising two main functional parts the organ of hearing or Cochlea For people with conductive losses, the BAHA, bypasses the external auditory canal and middle ear, stimulating the functioning cochlea. In Science and engineering, a conductor is a material which contains movable Electric charges. The ear canal ( external auditory meatus, external acoustic meatus) is a tube running from the Outer ear to the Middle ear. For people with unilateral hearing loss, the BAHA uses the skull to conduct the sound from the deaf side to the side with the functioning cochlea. Unilateral hearing loss (UHL or single-sided deafness (SSD is a type of Hearing impairment where there is normal hearing in one Ear and impaired hearing

Individuals under the age of 5 typically wear the BAHA device on a headband. Over age 5, a titanium "post" can be surgically embedded into the skull with a small abutment exposed outside the skin. Titanium (taɪˈteɪniəm is a Chemical element with the symbol Ti and Atomic number 22 An abutment is an end support of a Bridge Superstructure. Abutments are used for the following purposes to transmit the reaction of The BAHA sound processor sits on this abutment and transmits sound vibrations to the external abutment of the titanium implant. In Telecommunications transmission is the process of sending propagating and receiving an analogue or digital information signal over a physical point-to-point or Vibration refers to mechanical Oscillations about an equilibrium point. The implant vibrates the skull and inner ear, which stimulate the nerve fibers of the inner ear, allowing hearing. An axon or nerve fiber is a long slender projectionof a nerve cell or Neuron, that conducts electrical impulses away from the neuron's Cell

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 glasses and hearing aids frequently chose a type of hearing aid that was built into the temple pieces of the spectacles. Glasses, also called eyeglasses or spectacles, are frames bearing lenses worn in front of the Eyes normally for vision correction, Temple indicates the side of the head behind the Eyes The bone beneath is the Temporal bone. 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, people who use both glasses and hearing aids can use in-the-ear types, or rest a BTE neatly alongside the arm of the glasses. There still are some specialized situations where hearing aids built into the frame of eyeglasses can be useful, such as when a person has 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.

Recently, a new type of eyeglass aid was introduced. These 'hearing glasses' feature directional sensitivity: four microphones on each side of the frame effectively work as two directional microphones, which are able to discern between sound coming from the front and sound coming from the sides or back of the user [6]. This improves the Signal-to-noise ratio by allowing for amplification of the sound coming from the front, the direction in which the user is looking, and active noise control for sounds coming from the sides or back. Signal-to-noise ratio (often abbreviated SNR or S/N) is an Electrical engineering concept also used in other fields (such as scientific Measurements Active noise control (ANC (also known as noise cancellation, active noise reduction (ANR or antinoise) is a method for reducing unwanted Sound Only very recently has the technology required become small enough, in size, to be put in the frame of the glasses. As a recent addition to the market, the geographical market for this particular hearing aid is currently limited to a few European countries. Geography (from Greek γεωγραφία - geografia) is the study of the Earth and its lands features inhabitants and phenomena

Hearing aid technology

Wireless

A Phonak Campus S wireless FM system.
A Phonak Campus S wireless FM system.

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. A separate wireless microphone can be given to a partner to wear in a restaurant, in the car, during leisure time, in the shopping mall, at lectures, or during religious services. The voice is transmitted wirelessly to the hearing aids eliminating the effects of distance and background noise. In Acoustics and specifically in Acoustical engineering, background noise is any Sound other than the sound being monitored FM systems have shown to give the best speech understanding in noise of all available technologies. FM systems can also be hooked up to a TV or a stereo.

In developed countries FM systems are considered a cornerstone in the treatment of hearing loss in children. More and more adults discover the benefits of wireless FM systems as well, especially since transmitters with different microphone settings and Bluetooth for wireless cell phone communication have become available.

Many theatres and lecture halls are now equipped with assistive listening systems that transmit the sound directly from the stage; audience members can borrow suitable receivers and hear the program without background noise. Theatre (or theater, see spelling differences) is the branch of the Performing arts defined by Bernard Beckerman as what "occurs when one Brooklyn Book Festival crowd by David Shankbonejpg|thumb|An audience at the Brooklyn Book Festival in New York City. In some theatres and churches FM transmitters are available that work with the personal FM receivers of hearing instruments.

Directional microphones

Directional microphones are currently - after FM systems, see below - the best way to improve the signal to noise ratio, and thus, improve speech clarity in noise for the wearer. Signal-to-noise ratio (often abbreviated SNR or S/N) is an Electrical engineering concept also used in other fields (such as scientific Measurements

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. In physics interference is the addition ( superposition) of two or more Waves that result in a new wave pattern 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. An omnidirectional antenna is an antenna system which radiates power uniformly in one plane with a directive pattern shape in a perpendicular plane Some more-advanced models can electronically subtract signals so the user hears the directional signal minus the omnidirectional signal for improved background noise rejection.

Adaptive directional microphones are a further sophistication of the concept. Adaptive behavior is a type of Behavior that is used to adapt to another type of behavior or situation The hearing aid processor is able to distinguish noise as opposed to speech and automatically reduce the particular noise source from a certain angle. The limitations are at the identification level, where a noise that behaves similarly to a speech signal is difficult to identify, thus reducing efficacy. Efficacy is the capacity to produce a desired size of an effect under Ideal or Optimal conditions In severe background noise, the directional microphone is less efficient, however benefits may still exist.

Directional microphones unfortunately work best when the distance to the talker is not so large. But at close range there is often less need for directional microphones. At longer range and when there is more background noise, an FM system is currently the best technology that can bridge distance and suppress background noise at the same time.

Telecoil

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, induction loop systems and public address systems. Basic principle A traditional landline telephone system also known as "plain old telephone service" (POTS, commonly handles both signaling and audio information A public address or " PA " system is an electronic amplification system with a mixer, Amplifier and Loudspeakers used to In the UK, and some Scandinavian countries, hearing loop systems are widely used in churches, shops, railway stations, and other public places. Within the US, such installations are uncommon, and are often ineffectively and/or inconveniently installed.

T-coils are comprised of a metal core (or rod) around which ultra-fine wire is coiled. The M acro E xpansion T emplate A ttribute L anguage complements TAL, providing macros which allow the reuse of code across T-coils are also called induction coils because when the coil is placed in an electromagnetic (EM) field, an alternating electrical current is induced in the wire (Ross, 2002b; Ross, 2004). An induction coil or "spark coil" ( archaically known as a Ruhmkorff coil) is a type of Disruptive discharge Coil. Electromagnetism is the Physics of the Electromagnetic field: a field which exerts a Force on particles that possess the property of Electric current is the flow (movement of Electric charge. The SI unit of electric current is the Ampere. The T-coil detects EM energy and transduces (or converts) it to electrical energy. A transducer is a device usually electrical, electronic, Electro-mechanical, Electromagnetic, Photonic, or Photovoltaic Electric energy is the potential energy associated with the conservative Coulomb forces between Charged particles contained within a system, where T-coils can also be used to pick up magnetic signals, just as a microphone picks up an acoustic signal; the T-coil then sends the signal to the hearing aid circuit or processor for amplification. In Physics, magnetism is one of the Phenomena by which Materials exert attractive or repulsive Forces on other Materials. Acoustics is the interdisciplinary science that deals with the study of Sound, Ultrasound and Infrasound (all mechanical waves in gases liquids and solids

Since T-coils are effectively a wide-band receiver, interference is common. Such interference manifests as a buzzing sound, which varies in volume depending on the distance the wearer is from the source. Sources are electromagnetic fields, such as computers, electric cables, mobile phones, electric motors, airplane equipment, etc. Electromagnetism is the Physics of the Electromagnetic field: a field which exerts a Force on particles that possess the property of A computer is a Machine that manipulates data according to a list of instructions.

Since, by design, the sound processed through a T-coil is markedly different from a hearing aid's microphone. The frequency characteristics can differ, especially at the mid and low frequencies.

Legislation affecting use

In the United States, the Hearing Aid Compatibility Act of 1988 (HAC Act) requires that the Federal Communications Commission (FCC) ensure that all telephones manufactured or imported for use in the United States after August 1989, and all “essential” telephones, are hearing aid-compatible (through the use of a telecoil).

"Essential" phones are defined as "coin-operated telephones, telephones provided for emergency use, and other telephones frequently needed for use by persons using such hearing aids. " These might include workplace telephones, telephones in confined settings (like hospitals and nursing homes), and telephones in hotel and motel rooms. Secure telephones, as well as telephones used with public mobile and private radio services, are exempt from the HAC Act. "Secure" phones are defined as "telephones that are approved by the U. S. Government for the transmission of classified or sensitive voice communications. "

In 2003, the FCC adopted rules to make digital wireless telephones compatible with hearing aids and cochlear implants. A digital system uses discrete (discontinuous values usually but not always Symbolized Numerically (hence called "digital" to represent information for A cochlear implant (CI is a surgically implanted electronic device that provides a sense of Sound to a person who is profoundly deaf or severely hard of hearing Although analog wireless phones do not usually cause interference with hearing aids or cochlear implants, digital wireless phones often do because of electromagnetic energy emitted by the phone's antenna, backlight, or other components. An antenna is a Transducer designed to transmit or Receive electromagnetic waves In other words antennas convert electromagnetic waves into A backlight is the form of illumination used in a Liquid crystal display (LCD The FCC has set a timetable for the development and sale of digital wireless telephones that are compatible with hearing aids. This effort promises to increase the number of digital wireless telephones that are hearing aid-compatible.

DAI

Direct Audio Input (DAI) allows the hearing aid to be directly connected to an external audio source like a CD player or an assistive listening device (ALD). By its very nature, DAI is susceptible to far less electromagnetic interference, and yields a better quality audio signal as opposed to using a T-coil with standard headphones. Headphones (also known as earphones, earbuds, stereophones, headsets) are a pair of small Loudspeakers or less commonly a single

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:

Indications

Hearing aids are incapable of truly correcting a hearing loss; they are an aid to make sounds more accessible. Two primary issues minimize the effectiveness of hearing aids:

Adjustment to hearing aids

Purchase costs

Several industrialized countries supply free or heavily-discounted hearing aids through their publicly funded health care system. Publicly funded health care, or publicly funded healthcare, is Health care that is financed entirely or in majority part by citizens' tax payments instead of through

Australia

The Australian Department of Health and Ageing provides eligible Australian citizens and residents with a basic hearing aid free-of-charge, though recipients can pay a "top up" charge if they wish to upgrade to a hearing aid with more or better features. For a topic outline on this subject see List of basic Australia topics. The Department of Health and Ageing is an Australian Government department Maintenance of these hearing aids and a regular supply of batteries is also provided, on payment of a small annual maintenance fee. [7]

Canada

In Canada, health care is a responsibility of the provinces. Country to "Dominion of Canada" or "Canadian Federation" or anything else please read the Talk Page The provinces and territories of Canada combine to make up the world's second largest country in total area. In the province of Ontario, the price of hearing aids is partially reimbursed through the Assistive Devices Program of the Ministry of Health and Long-Term Care, up to $500 for each hearing aid, every three years. Ontario (ɒnˈtɛrioʊ is a province located in the central part of Canada, the largest by population and second largest after Quebec The Ministry of Health and Long-Term Care is the Government of Ontario ministry responsible for administering the Health care system and providing services through such programs Like eye appointments, audiological appointments are no longer covered through the provincial public health plan. Audiometric testing can still easily be obtained, often free of charge, in private sector hearing aid clinics and some ear, nose and throat doctors offices. Hearing aids are often covered to some extent by private insurance or in some cases through government programs such as Department of Veteran Affairs or Workplace Safety & Insurance Board.

Iceland

Social Insurance pays a one time fee of ISK 30. 000 for any kind of hearing aid, however the rules are complicated and requires that both ears have a significant hearing loss in order to qualify for reimbursement. BTE hearing aids range from ISK 60. 000 ISK to 300. 000 ISK. [8]

UK

Within the UK, the NHS provides BTE hearing aids to NHS patients, on long-term loan, free of charge. The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom, the UK or Britain,is a Sovereign state located Though BTEs are often the only style available, and private purchases are usually necessary if a recipient desires a different style. Private purchases can cost between £600 to £3,500. [9]

US

Most private US health care providers do not provide coverage for hearing aids, so all costs are usually borne by the recipient. Such costs can vary between $500 to $5,000. Though if an adult has a hearing loss which substantially limits major life activities, some state-run vocational rehabilitation programs can provide upwards of full financial assistance. The Vocational Rehabilitation Act of 1973 Title V was put in place to correct the problem of discrimination against people with disabilities in the United States. Severe and profound hearing loss often falls within the "substantially limiting" category. [10]

The cost of hearing aids is a tax-deductible medical expense. Individual taxpayers in the United States are allowed a choice when preparing their Federal income Tax returns After computing their Adjusted gross income (AGI taxpayers [11]

Notes and references

  1. ^ Comparison of Hearing Aids Over the 20th Century. Ear & Hearing. 21(6):625-639, December 2000. Bentler, Ruth A. ; Duve, and Monica R.
  2. ^ http://www.hearingcenter.com/Questions/Q_ear-horn.html Ear Horn Q&A. Accessed 6 Dec 2007.
  3. ^ The Hearing Aid as Fashion Statement, by Anne Eisenberg, September 24, 2005 on NYTimes. com. Accessed 24 Nov 2006.
  4. ^ ELVAS Sightings - Hearing Aid or Headset, by Paul Dybala, Ph. D. , March 6, 2006 on AudiologyOnline. com. Accessed 3 May 2007.
  5. ^ The "Occlusion Effect" -- What it is, and What to Do About it, by Mark Ross, January, 2004 in Hearing Loss. Accessed 25 Nov 2007.
  6. ^ Netherlands: Dutch Unveil 'Varibel' - The Eyeglasses That Hear, Publish Date: March 01, 2007, Related Company Website: www, varibel. nl. Accessed 10 Feb 2008.
  7. ^ Understanding the Australian Government Hearing Services Program. Retrieved on 2007-12-04. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. "December 4th" redirects here For the song by Jay-Z, see December 4th (song.
  8. ^ Social Insurance Administration - Iceland Accessed 30 November 2007
  9. ^ NHS hearing aid service fact sheet Accessed 26 November 2007
  10. ^ The U.S. Equal Employment Opportunity Commission: Questions and Answers about Deafness and Hearing Impairments in the Workplace and the Americans with Disabilities Act Accessed 26 November 2007
  11. ^ Topic 502 - Medical and Dental Expenses Accessed 26 November 2007

See also

External links

Dictionary

hearing aid

-noun

  1. A device used to help the hard of hearing hear sounds better.
© 2009 citizendia.org; parts available under the terms of GNU Free Documentation License, from http://en.wikipedia.org
 Dapyx Software network: MP3 Explorer | Ebook Manager | Zenithic