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Assistive Listening Systems

Induction Loops	FM systems	Infrared (IR)
Captioning	Communication Access Realtime Translations (CART)	Computer Assisted Notetaking (CAN)
C-Print	TypeWell

Induction Loops

Induction technology was originally designed for use at schools for the deaf. Induction loop technology by magnetic induction is a basic principle of electronics.

How does induction work? First an electrical current is amplified and passed through a loop of wire. As a result a magnetic field is generated around the area of the wire. The magnetic field that is created varies in direct proportion to the strength and frequency of the signal (or sound) being transmitted. If another wire is placed within the range of the field of the first wire, an identical electrical current is produced in it. The second current can be amplified and converted into an exact duplicate of the original sound signal.

People also take advantage of this technology by connecting ‘neckloops’ to telephones, music players, and televisions to hear sound without using headphones. With neckloops, an induction loop is place around the neck and the sound is delivered directly to the telecoils through induction.

There are also, portable ‘3D’ loops which can be placed on top of counters to serve people with hearing loss. The back of the device has a microphone which faces the person without hearing loss behind the counter. The induction loop faces the person with hearing loss on the opposite side of the counter. The person with hearing loss only needs to turn on his or her telecoils to benefit from the system.

Some advantages of inductions loops include:

People with telecoils in their hearing aids do not need to use receivers.

It is accessible to people who do not use hearing aids or have hearing aids without telecoils (an induction receiver unit must be purchased with appropriate attachments such as headphones or ear buds).

This is a lower cost and lower maintenance system as less equipment needs to be purchased.

It is easier to use than other systems.

Loops may be portable.

It can work in transient situations such as ticket counters, car interiors, and drive through windows.

Some disadvantages of induction loops include:

It may not work well with hearing aids that have weak telecoils (an audiologist may be able to adjust the telecoils).

Not all hearing aids have telecoils.

Loops may have dead spots, or spots within the loop that are not as strong.

Two loops place near each other may “leak” sound.

To find CART providers please go to this link: http://cart.ncraonline.org/Directory/locator.htm

FM systems

FM Systems work like a miniature radio station. The transmitter has a microphone and sends FM waves to a receiver. In the United States special frequencies are set aside for users of FM systems so that there is no interference from outside FM transmissions.

Not all FM systems are compatible with one another as there are different frequencies or ‘channels’ that the systems can send or receive. This works out nicely, when there are two hard of hearing children in the same school. If both children were using the same FM channel, one may pick up the ‘broadcast’ of the wrong classroom. In many systems today the channel can be changed on the transmitter or receiver.

There are also smaller transmitters available. One company (Phonak) has made receiver small enough to fit inside certain models of their behind-the-ear hearing aids. Here is an example of one type of transmitter. The device is smaller than most cell phones.

Some advantages of FM systems include:

An FM system is generally very easy to set up and highly portable.
A person is free to move around and even walk to different rooms and can still receive the broadcast. Because FM systems are durable and portable, they are most often used in educations settings for children with hearing loss.
An FM system can be used with a very broad range of hearing loss.
F M systems can be used indoors or outdoors.

Some disadvantages of FM include:

Privacy may be an issue as an FM ‘broadcast’ can easily be “tapped”. This is an important consideration for courtrooms.
Privacy may also be an issue when multiple personal FM systems are being used in groups such as meetings for people with hearing loss.
Multiple FM receiver units are expensive, may require a lot of maintenance (with batteries) and can be difficult to store.

Infared Systems (IR)

An infrared system uses invisible beams of light (this is the same technology used by your remote control). Infrared light waves are transmitted by an array of LED’s (light emitting diodes) that are located on a panel. The receivers have a detector that senses the infrared light and converts the signal to sound.

Some advantages of an IR system include:

Privacy, the transmission of IR is confined within the walls of a room.
Some experts believe that IR produces the best sound quality.

Some disadvantages of an IR system include:
The lack of portability, IR systems require a high level of electrical output and need to be plugged in.
IR systems generally work best in darker environments, as too much light can interfere with the system (they do not work well outdoors during the daytime as the largest source of IR in our solar system, the Sun, causes interference).
Shadows or blockages of either the transmitter or receiver can interfere or cut out transmission (this is why it is sometimes referred to as the ‘remote control’ of assistive technology, like a television remote control the transmitter and receiver must be facing one another with no major impedances).

Captioning

Closed captioning is veiled within the video signal. A special decoder is needed to display the captions on the screen.

Open captioning is when the captions are visible to everyone without a decoder. The Television Decoder Circuitry Act of 1990 mandates that since July 1993, all televisions manufactured for sale in the U.S. must contain a built-in caption decoder if the picture tube is 13" or larger. Closed captions on television programs most often have a black background and white text, although different combinations are possible and utilized on some programs.

Communication Access Realtime Translations (CART)

CART or Communication Access Realtime Translation is the verbatim, near instantaneous conversion of spoken language into text. A stenotype machine, notebook computer and realtime software is used to produce the text. The text is usually displayed by either on a screen by a projector connected to the notebook computer, or on a notebook computer or computer monitor. CART is usually utilized by people with hearing loss who use spoken language as a primary mode of communication. However, some culturally Deaf people (whose primary mode of communication is a sign language) use CART in situations such as graduate level anatomy classes, as it may be easier to read all of the specific terminology rather than have signs improvised on the spot, or use finger spelling.

To be able to effectively use CART, the level or literacy of the individual with hearing loss should be considered (for example, CART may not be an effective accommodation for a pre-schooler with hearing loss, as they have not yet learned how to read). People who use sign language to communicate expressively need a sign language interpreter instead of CART, or in addition to CART to interpret for non-signers. CART is also often referred to as “real time captioning.”

CART can cost between $40 and $200 an hour. There is usually a two or three hour minimum. Equipment, travel and preparation time to build the dictionary of names and terms specific to the event. Experience of the CART provider is also a consideration.

Computer Assisted Notetaking (CAN)

CAN or Computer Assisted Notetaking is a method of providing notes for people with hearing loss during a meeting using the services of a typist who uses a normal (QWERTY) keyboard. Unlike CART which can provide instant transcription (sometimes more than 225 words a minute) CAN does not usually come as close to verbatim when presenting the text. There are some professional CAN operators who are fast typists and use special software and pre-trained codes to enhance their note taking speed. An advantage of CAN over CART is that it may be less expensive depending on travel times of the CAN operator and the equipment available.

Both CART and CAN services can be provided from remote locations through a telephone line.

C-Print

C-Print is a speech-to-text system developed at the National Technical Institute for the Deaf (NTID), a college of Rochester Institute of Technology (RIT). C-Print uses special software which uses an abbreviation system and/or automatic voice recognition (ASR) to produce near-instantaneous text. C-Print is rarely as accurate as CART (although it may be in some circumstances), and it is typically more accurate and quick than CAN.

TypeWell

TypeWell is a similar system to C-Print. It also uses an abbreviation software. Like C-Print, it is not quite as accurate as CART and is typically less expensive than CART. Instead of providing a verbatim transcription, both TypeWell and C-Print operators sometimes condense information, and put more emphasis on conveying the meaning rather than conveying what is said verbatim (which is not always possible due to constraints on speed of transcription).

CAN, C-Print and Typewell generally cost between ten and sixty dollars an hour. Considerations such as time needed, experience of operator, equipment used and travel expenses should be considered in final cost.