technology for hearing devices part v-a technology for hearing devices part v-a educ 477/689i...

Technology For HearingTechnology For HearingDevices Part V-ADevices Part V-A

EDUC 477/689I

Devices Part V

March 2005 AT 2005 Devices Part VA Davina Pruitt-Mentle2

Technology For HearingTechnology For Hearing

• General Information on Hearing Impairments:– 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.



• Definitions: – Hard of Hearing (some degree of residual

hearing). – Deafness (very little hearing; difficulty in

acquiring language).



• Challenges faced by people with hearing impairment acquired before age 2: – Isolation from normal means of learning

language. – Lack of linguistic frame of reference for

learning to speak, write and read.



• Common problems experienced by persons with a hearing impairment: – 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.



• 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.

– Assistive Communication Devices for Persons with Hearing Impairments

http://en.wikipedia.org/wiki/Deafness

http://en.wikipedia.org/wiki/Deafness



• Types of Assistive Technology for Persons with Hearing Impairment and Deafness– Assisted Listening Devices– Telecommunication Devices for the Deaf– Altering Devices



• 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.

– 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.



• Assisted Listening Devices (ALDs) - Hearing Aids

• the most popular - and most commonly used - ALD.

• Visit the sites below to learn about what a hearing aid is and how they work.

– How Does a Hearing Aid Work?

– What is a Hearing Aid?

• As you review these sites, remember that hearing aids do one thing - amplify sounds. The specific amplification levels and frequencies are determined from an audiological exam. Also, each aid has advantages and disadvantages.

http://www.ftc.gov/bcp/conline/pubs/health/hearing.htm



• Probably one of the most significant aspects of the standard hearing aid is the telecoil.

• This component allows the person with a hearing aid to combine their aid with other ALDs to be most productive in a variety of settings.



• Some of the more frequently cited limitations:– 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



• Limitations are compounded by the fact that persons with hearing impairments, especially acquired hearing impairments, already have foreground/background noise filtering problems and have difficulty with echoing and reverberating sounds.

• Putting a hearing aid on a child is not a simple process.

• Hearing aids do not solve all your problems!



• Assisted Listening Devices - 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.



• Assisted Listening Devices - Induction Loops and FM or Infrared (IR) Systems

• Both the hardwired and wireless systems have four basic components:– Microphone– Transmitter– Receiver– Connection to the Aid



Microphone• All ALDs have a microphone.

• picks up environmental sounds and transmits them to a receiver.

• The positioning of the microphone is important

• 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.



Transmitter

• 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.



Receiver

• 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.

• Some receivers accept induction loops (you will learn about these soon) through a jack included in the unit.

• All receivers are fairly small and light.


Technology For HearingTechnology For HearingConnection to the Hearing

Aid

• connection to the hearing aid.

• These connections can take one of several forms. – a headphone set that the

user wears over his or her hearing aid

– a direct connection (wire) between the receiver and the hearing aid

– an induction loop that is worn around the user's neck



• 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.

– The person is physically connected (plugged into) the amplification system.

– 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 a television program.



Advantages of a hardwired ALD:

• 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)



• The second general type of ALD, a wireless systems– Allow 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



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



Induction Loop Systems

• 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.



Induction Loop Systems

• 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)



• 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.



FM Systems

• 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.


Technology For HearingTechnology For HearingFM Systems

• 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.



• Infrared Systems– Infrared systems, the last of the three types of

commonly used ALDs, work much the same as the FM system



• Infrared Systems– 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.



• Infrared Systems– Because of this

disadvantage most IR systems are located near the ceiling line or high on the walls of public gathering rooms.



Assisted Listening Devices

• For a summary of distinct advantages and disadvantages, visit

• Advantages and Disadvantages of ALDs

http://www.rldrake.com/al/Assliss.html

http://www.rldrake.com/al/Assliss.html


Technology For HearingTechnology For Hearing• Telecommunication devices

• include any aid that helps the person with a hearing impairment or deafness use conventional telecommunication devices (telephones).

• Telecommunication devices can include amplifiers that connect to existing handsets, special amplified handsets and, for individuals who are not able to hear or understand speech (deafness), telecommunication devices for the deaf.

• Not a device per se.-Telephone relay services assist a person to use standard technology and communicate with hearing persons without the need for modified telephones on both ends of the connection.



• Alerting or Signaling Devices

• alert the user to situations that they may not otherwise hear (doorbells, baby crying).

• Alerting devices may produce louder sounds or alter the frequency of existing sounds, change the sound to a visual signal (flashing light), or convert the sound to a tactile signal (vibration).



• Next we will look at:– Technology for Persons with Hearing

Impairment - Telecommunication & Alerting Devices

technology for hearing devices part v-a technology for hearing devices part v-a educ 477/689i...

Documents

hearing devices

hearing challenges

hearing definitions

hearing aid work

little hearing difficulty

hearing common problems

hearing general information

degree of residual hearing