1. Technology for Hearing Impairments

2. Statistics
Between 21 and 28 million Americans are affected by a hearing impairment.
1 out of 10 Americans have a hearing impairment.
60% of persons over the age of 65 have a hearing impairment.
Hearing impairment is considered a hidden disability.

3. Definitions Hard of Hearing (some degree of residual hearing).
Deafness (very little hearing; difficulty in acquiring language)

4. Challenges faced with acquired before 2 years of age
Isolation from normal means of learning language.
Lack of linguistic frame of reference for learning to speak, write and read

5. Common problems experienced by persons with hearing impairments
Difficulty discriminating between background noise and the speaker
Difficulty filtering out the reverberated sounds from the direct signal
Difficulty with speech discrimination and a decrease in signal-to-noise ratio when the distances between the speaker and listener increases
Definition: [n]  the ratio of signal intensity to noise intensity

6. Types of AT for Hearing Impairments
Assisted Listening Devices
Telecommunications devices for persons who are deaf
Alerting Devices
Types of Assistive Technology for Persons with Hearing Impairment and Deafness
There are many ways of trying to classify the types of devices that are available to persons with hearing impairments or who are deaf. Visit the site below to see one way to organize this large group of devices.
Decreasing reverberation and other helpful strategies
As you can see, this site lists many different types of devices. Being a person who needs organization to make sense of new information, I break technology for persons with hearing impairment into three distict types listed below. Click on each button to learn more about each category of hearing technology

7. ADLs

8. Assisted Listening Devices
Any aid or device that helps the person to detect sound that he or she might otherwise miss because of their hearing impairment. Probably the most common assisted listening device -and the one we are most familiar with - is a hearing aid. Other ALDs include devices that alter the frequency of telephone or doorbell alarms to accommodate a high or low frequency hearing loss and infrared, radio frequency (sound familiar?), or induction loop systems.

9. Hearing Aids Most popular and most commonly used ALD Problems:
hearing aids cannot always discriminate between foreground and background sounds
these devices have difficulty separating one voice from others in noisy environment
persons using hearing aids report difficulties focusing on one sound in an environment to the exclusion of others.
echos and reverberations cause specific problems for persons with hearing impairments who use hearing aids
About Hearing Aids - About Hearing Loss - Boys Town National Research Hospital
Hearing aids come in a variety of types and models.
there is a term you should be familiar with. The signal-to-noise ratio is an important dynamic to consider in looking at a person's ability to use their residual hearing abilities.
Remember that hearing aids do one thing - amplify sounds. Since all sounds are amplified with a hearing aid, persons often need to learn how to filter out irrelevant sounds (the air conditioner, fans, wind, etc.) so that they can concentrate on the important sounds in their environment.
We all do this automatically. For some people, especially persons who have not heard well in quite some time, if ever, this is a difficult task.. The other point to remember before we begin learning about hearing aids is that the specific amplification levels and frequencies are determined from an audiological exam. T
he audiologist is the person who is able to perform the proper tests to determine the unique characteristics and needs of each person. In addition, these professionals are well versed on the advantages and disadvantages of each hearing aid option.
Probably one of the most significant aspects of the standard hearing aid is the telecoil. This component will allow the peson with hearing aids to combine their aid with other ALDs to be most productive in a variety of settings.

10. What is a hearing aid?
A hearing aid is an electronic, battery-operated device that amplifies and changes sound to allow for improved communication.
Hearing aids receive sound through a microphone, which then converts the sound waves to electrical signals. The amplifier increases the loudness of the signals and then sends the sound to the ear through a speaker.
There are four basic styles of hearing aids for people with sensorineural hearing loss:
In-the-Ear (ITE) hearing aids fit completely in the outer ear and are used for mild to severe hearing loss. The case, which holds the components, is made of hard plastic. ITE aids can accommodate added technical mechanisms such as a telecoil, a small magnetic coil contained in the hearing aid that improves sound transmission during telephone calls. ITE aids can be damaged by earwax and ear drainage, and their small size can cause adjustment problems and feedback. They are not usually worn by children because the casings need to be replaced as the ear grows.
Behind-the-Ear (BTE) hearing aids are worn behind the ear and are connected to a plastic earmold that fits inside the outer ear. The components are held in a case behind the ear. Sound travels through the earmold into the ear. BTE aids are used by people of all ages for mild to profound hearing loss. Poorly fitting BTE earmolds may cause feedback, a whistle sound caused by the fit of the hearing aid or by buildup of earwax or fluid.
Canal Aids fit into the ear canal and are available in two sizes. The In-the-Canal (ITC) hearing aid is customized to fit the size and shape of the ear canal and is used for mild or moderately severe hearing loss. A Completely-in-Canal (CIC) hearing aid is largely concealed in the ear canal and is used for mild to moderately severe hearing loss. Because of their small size, canal aids may be difficult for the user to adjust and remove, and may not be able to hold additional devices, such as a telecoil. Canal aids can also be damaged by earwax and ear drainage. They are not typically recommended for children.
Body Aids are used by people with profound hearing loss. The aid is attached to a belt or a pocket and connected to the ear by a wire. Because of its large size, it is able to incorporate many signal processing options, but it is usually used only when other types of aids cannot be used.

11. A Function Switch: Usually M-T-O (Microphone, Telecoil and Off)
B Battery: Supplies power to the amplifier
C Microphone: Converts acoustic energy to electrical energy.
D T-Coil: Converts magnetic energy to electrical energy.
E Amplifier or Circuit: Increases the stregth of the electrical signal. Also filters and modifies the response of the hearing aid to match the hearing loss of the user.
F Volume (Gain) control. Allows the user to increase or decrease the over-all level of the sound after the amplifier. Many newer hearing aids have automatic gain control.
G Receiver: Converts electrical energy to acoustic energy.
H Sound hook (tonal tube): Delivers the sound from receiver to the ear mold. May be filtered to further adjust the signal to match the hearing loss.

12. Choosing a Hearing Aid
Selection will greatly depend on the nature and extent of your hearing loss and the size and shape of the outer ear and canal
Some conditions (i.e. ear drainage) may prevent a person from wearing hearing aids that block the ear or canal
A few other factors to keep in mind as you choose your hearing aid:
Aesthetic considerations play a large role for some wearers, who may prefer wearing nearly invisible aids.
Some people prefer a hearing aid that is visible but blends with their skin tone.
Small hearing aids (ITCs or CICs) also have tiny batteries and those with limited dexterity or sight problems may find these difficult to operate.
It is a good idea to carefully examine the hearing aid's warranty, both as it applies to the device and battery life. And will the manufacturer provide a temporary replacement if your new hearing aid requires repairs?
Check first with your health insurance provider to find out if the device is covered.
Some suppliers offer trial periods to ensure the person is happy with their new hearing aid. But make sure to ask whether or not there will be a charge for this service.
In case of future problems, where can your new hearing aid be repaired? And will you be able to get a loaner while your hearing aid is being serviced?

13. Sound Field Systems 2 1
Induction Loops and FM or Infrared (IR) Systems
Other ALDs increase the volume of specific sounds in the environment and allow the user of a hearing aid to focus their hearing abilities. ALDs come in two forms: hardwired and wireless systems. Both the hardwired and wireless systems have three basic components:
Receiver: The receiver unit for ALDs accepts the broadcast from the transmitter, converts the broadcast to sound, and transmits the sound to the user. Some receivers are worn around the person's neck; others are placed on a surface near the person. In addition, some receivers accept induction loops (you will learn about these soon) through a jack included in the unit. Regardless, all receivers are fairly small and light.
The second component of all ALDs is the transmitter. Each system you will learn about in the next section contains a transmitter. These transmitters receive the sounds gathered by the microphone, convert these sounds to another form of transmission (infrared light, radio waves, or electromagnetic current), and broadcast this alternative transmission to the person.
All ALDs have a microphone. The microphone functions similar to all standard microphones; that is, it picks up environmental sounds and transmits them to a receiver. The positioning of the microphone is important to the overall functioning of the ALD for the person with a hearing impairment. You want the microphone close enough to the source of the sound (be that a voice, orchestra, radio or television set) to isolate that sound from the background noise. Properly positioned microphones create a favorable Signal to Noise Ratio and allow the person with a hearing impairment to focus on specific sounds.
4. The last component of the ALD system is a connection to the hearing aid. These connections can take one of several forms. The connection may be:
a) a headphone set that the user wears over his or her hearing aid
b) a direct connection (wire) between the receiver and the hearing aid
c) an induction loop that is worn around the user's neck 3 4

14. Hardwired or Wireless?
Hardwired systems tether the individual to the amplification devices
A second distinction with ALDs is whether the system is hardwired or wireless. Most ALDs that are commonly used today are wireless.
Hardwired systems tether the individual to the amplification devices. That is, the person is physically connected (plugged into) the amplification system. This type of system will pick up sounds with their microphone and transmit these sounds to the person through a wire attached to an earphone or directly to the hearing aid. Hardwired systems typically consist of two elements: a direct plug-in connection between the user and the sound source - for example a TV - and an extension microphone that attaches to the sound source An example of a hardwired system would be a person who uses a remote microphone attached to their hearing aid to watch atelevision program.

15. Hardwired or Wireless? Advantages of a hardwired ALD:
this is an alternative amplification system for the person with a hearing aid
good for providing temporary amplification (watching TV in a noisy environment)
good for one-to-one communication (the speaker can have the microphone and place it directly before their mouth, increasing the volume of the specific sound source -their voice)
portability (easy to carry and connect to a variety of device)
lower cost
easier to use that other ALDs (hardwired systems often do not require much training to operate)
Disadvantages of a hardwired ALD:
the location and positioning of wires may be troublesome
the person using a hardwired system has limited seating options (they can only sit in certain locations to directly connect to the sound source)

16. Hardwired or Wireless?
Hardwired systems tether the individual to the amplification devices
The second general type of ALD, a wireless system, allows the user more access to their environment because the devices are not tethered.
In a wireless system the sounds are passed from the transmitter to the receiver by either infrared light beams or through radio frequency waves. Wireless systems come in three configurations.:
Induction loop systems
FM systems
Infrared systems

17. Induction Loop Systems
Induction loop systems are not as commonly used as the other wireless systems, but are still present in many meeting rooms (housed in walls or under the carpet) and auditoriums.
With an induction loop system the microphone picks up the sound source (speaker, television, radio, etc) and the amplifier converts the sound signals to electromagnetic waves.
These electromagnetic waves are then broadcast through a wire (the induction loop) that is placed around the person or, in some instances, worn around the person's neck (a personal induction loop system).
The person with a hearing impairment adjusts their hearing aid to the telecoil setting to pick up the electromagnetic signals. The hearing aid then converts the electromagnetic signals into sound that is amplified by the hearing aid.
Because the broadcast of an induction loop is restricted to a specific area, these devices are sometimes thought of as a semi-hardwired system because the user must remain within the enclosed broadcast area (inside the loop).

18. FM Systems
A FM system (radio broadcast) uses a FCC-restricted set of radio frequency bands to broadcast sound to a person with a hearing impairment.
This system contains a transmitter and a receiver. Whereas the induction loop converted sound into electromagnetic energy, the FM system converts the sound to radio frequency waves that can be broadcast within a limited range.
The use, however, does not need to remain within a small area (as with loops) but can move freely about the room and sometimes leave the room (because radio frequency waves pass through walls). The person wears a receiver - usually on their chest - that receives the radio waves and converts them into sound signals to be amplified by the hearing aid.
The user may connect to the hearing aid directly by plugging the receiver into their hearing aid, attach earphones to the receiver and place the headset over their hearing aid, connect a personal induction loop to the receiver

19. Infrared Systems
Infrared systems, the last of the three types of commonly used ALDs, work much the same as the FM system.
The main difference between the two systems is, in an infrared device, the sound is converted to a series of infrared light beams that are broadcast throughout the environment.
Here also, the user is free to move about the room or sit where they desire as long as they are facing the broadcast unit.
Whereas FM waves can penetrate walls and intervening objects, infrared beams are blocked and the user must reestablish a direct line-of-sight with the broadcast unit.
Because of this disadvantage most IR systems are located near the ceiling line or high on the walls of public gathering rooms.

20. Wireless Adv. and Disadv.
Advantages and Disadvantages of Wireless systems
An Overview of Assistive Listening Systems

21. Telecommunication and Alerting Devices

22. Telecommunication Technology
Amplification devices
Telecommunication Devices for the Deaf (TDD)
Telephone Relay Services
Alerting Devices
There are two basic difficulties between people who are hard of hearing and those who cannot understand speech (deaf) when it comes to using telecommunication devices.
First, the sound quality is not always the best when conveyed over telephone lines. You may have noticed some high pitched hissing, possibly some background noises (including muffled communication from another person's call), static, or distorted voice quality when you are using the phone. When a person has a hearing impairment, these sounds tend to exaggerate the effect of the hearing impairment by the distorting overall quality of any sounds.
Second, phone conversations lack the face-to-face quality of in person communication. This hinders someone who is having trouble with hearing sounds from being able to use facial cues to "fill in" the missing content. They cannot rely on facial expression, gestures, and sometimes lip reading as aids to understanding spoken communication. This is where telecommunication devices fulfill an important role for persons with hearing impairments or deafness.
Technology to help persons with hearing impairment use the telephone or other telecommunication equipment is generally broken down into three catetories of devices:

23. Amplification Devices
Amplified Handsets
Modular Amplifiers
Portable Amplifiers
The first type of telecommunication device would be an amplification device. As the name implies, amplification devices take the normal auditory signal and boost the level overall or, in some instances, boost selective frequencies (usually low or high) to match the person's hearing profile. Most amplification devices can be fitted over the earpiece of the phone, are integrated into the standard handset, or can be attached to the phone through modular wiring. Regardless, these devices work with the standard telecommunication technology and require little, if any, modifications. For that reason, they are a very flexible, inexpensive, and convenient type of ALD for many persons with hearing impairment.
The three most common types of amplification devices for the person with a hearing impairment who wants to use the standard phone are:
Amplified Handsets: This allows the user to adjust the sound from normal volume all the way to a 30 dB (decibel) increase. All amplified handsets must be connected to a modularized phone system. Often, to avoid incompatibility, these handsets must be connected to a phone of the same make and model. To review a few amplified phones, click on the links below.
Modular Amplifiers: Modular amplifiers are typically attached between the handset and the base phone unit. Some units allow the user to adjust the level of amplification; others (usually the less expensive models) allow only one level of amplificaiton. These modular amplifiers can only be attached to modular phones (not cell phones, portable phones, etc.). Some modular amplifers have difficulties with different types of phones so you need to check for compatibility before purchasing one of these devices.
Portable amplifiers: Portable Amplifiers are small, detachable amplifiers that attach to the telephone handset fitting over the earpiece. These device intercept the sound signal leaving the handset and boost that signal and/or convert the signal to electromagnetic signals that the hearing aid's telecoil can accept. Portable amplifiers can be used in conjunction with a hearing aid or apart from one.

24. TDDs
TTYs: (TDDs as they are now called) use text to communicate over standard telephone lines.
TTDs: The TTY unit itself converts auditory tones into text characters that are then displayed as a text message. To work, a TTY must be communicating with another TTY. The person sending the message types his or her message into the TTY device on their end. Their TTY converts the keystrokes into auditory tones that are similar to the tones you hear when you dial a telephone number. These tones are sent across the voice telephone lines to the receiving TTY. This TTY accepts the auditory tones and converts them into characters and displays these on the text display or prints them onto a printer (if included in the TTY).
Even though TTYs come in a variety of shapes, sizes, and have different functions, they generally have similar components:
Over time TTY users have developed an etiquette for conversations to alert each other when the person is finished with their comment, statement, question (the user types GA and the end of their message - "Go Ahead"), when one person has completed the call (the user types SK - "Stop Keying") and when the conversation is complete and the connection can be broken (SK, SK)

25. TTY Etiquette
FAQs and General TTY Etiquette Tips for New Users of the TTY---Some of the tips suggested are similar to new users of which many more deaf and hh persons are using in favor of the TTY

26. Telephone Relay Services
allow a user with a TDD to communicate with persons or businesses that do not have these devices. All relay services are subsidized by a small fee included in standard phone line services.
Payphone Relay Service
Telecommunications Relay Services
IP Relay Service

27. Alerting Devices
An alerting device is any aid or device that alerts a person with a hearing impairment to the environmental sounds that are typically conveyed through auditory means.
For example, the auditory sound of a doorbell may not be recognized by a person with a high frequency hearing loss. An alerting device can take that auditory signal, convert the sound into a visual cue (a flashing light), and alert the person that someone has pushed the doorbell.
Because alerting devices help the person to live independently and control their environment, they are sometimes listed under environmental control units (ECUs). The.ECUs we discussed earlier in the Access unit were primarily designed for a person with a physical or cognitive impairment. Alerting devices, on the other hand, are specifically designed for a person with a moderate to profound hearing loss.
Alerting devices can be used full-time in conjunction with a hearing aid or some other form of assisted listening device (ALD), or they may be used only part-time when the user is not using an ALD. Regardless of their pattern of use, all alerting devices do three things:
Detect and environmental sound
Convert the sound
Signal the person with the hearing impairment

28. Alerting Device Features
Detect to an environmental sound
Convert to sound
Signal the person
Detect to an Environmental Sound
Most alerting devices contain a built-in microphone that detects the sound. Some alerting devices, however, are hard wired to the device by a physical connection. In this way, the alerting device becomes part of the original device (doorbell, telephone, etc.) and makes use of the existing circuitry. Regardless of which method the device uses to detect the sound, the alerting device is positioned close to the sound producing device.
Convert to Sound
Alerting devices typically convert the sound to another sensory signal (tactile or visual). Some alerting devices will change the frequency of the auditory signal. For example, a telephone alerting device may convert the high frequency ring to a low frequency buzz to allow a user to use their residual low frequency hearing abilities.
Signal the Person
All alerting devices will use the alternative sensory channel (tactile, visual, or modified auditory) to alert the user that an auditory signal has been issued. In instances where multiple alerts are possible (fire alarm, telephone, doorbell, baby crying, microwave beep, dryer buzz) the person may use more than one alerting device or use an alerting device that allows them to change the frequency or duration of the modified signal. As an example of this latter situation, a person may have the light flash at a different rate for each of the devices listed above. This allows the person with a hearing impairment to differentiate between multiple devices.

29. Some examples of alerting devices include:
sounds converted to visual stimulus
flashing lights, strobe light, colored light on/off
sounds converted into tactile stimulus
vibration, fan, heater
Sound modifications
changing a high frequency sound to a low frequency sound or vice versa

30. Devices Clocks and alarm systems Warning devices and detectors
Clocks & Wake Up Alarm Systems for deaf and hard of hearing
Warning devices and detectors
Warning Devices for deaf and hard of hearing
Loud phone ringers
Phone Ringers for deaf and hard of hearing
Other alarm systems