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Jeri Lynn Hoffman
26210 Emery Road
Warrensville Hts., Ohio 44128
Scanning can be used if no method of direct select can be utilized for augmentative communication. If the person we are working with has a visual impairment along with motoric considerations, we are forced to use auditory scanning possibly combined with visual scanning.
Auditory scanning consists of presenting auditory information, usually words or phrases, in a predetermined sequence. To perform the task of auditory scanning, many parameters must be addressed.
The person must be able to make choices and to make those choices known. To work on decision making, the person must have preferences and the preferences must be reinforceable. The person must have a signal or a mode of indication. The person must use the signal to indicate a desire for an object or an event and they must use the signal to indicate a choice between two objects or events. You must look at the person's activities to decide where choices might be provided.
In the beginning, you will want to give choices where both answers are correct. Later you will give choices were there is a high preference choice and a low preference choice.
There are a variety of methods that the person can use to indicate a choice. It can be as simple as making a gross sound or gesture or it can be more refined using a switch. If you are going to use a switch, the person must have one reliable, consistent, voluntary movement. In choosing the site of the switch, the person's position must be considered and where that person will be located (in a wheelchair, desk, bed).
Switches vary with respect to force, feedback, amount of travel, amount of play, size, weight, moisture resistance and safety. There are also different types of switches. Push switches requires the person to apply force. Pull switches require the person to pull away from the switch. One example of a pull switch is the String Switch from Ablenet. A grasp type switch requires squeezing of the switch and a flex switch requires bending of the switch. A mercury switch is activated by position, not pressure. A pneumatic switch is a sip and puff switch. An infrared switch is one like Innocomp's BlinkSwitch. It works by changes in the reflection of light to the infrared signal. The Untouchable Buddy from TASH is an example of a zero pressure switch. It only requires the person to move to it but does not require any pressure.
Training in locating and touching the switch can begin with your hand. Hold your hand where the switch would be and have the person move their body part to your hand. This begins with training of initiating the switch response and continues with the training of holding and releasing the switch.
The amount and type of vision the person has must be considered. Eighty percent of all individuals classified as legally blind have residual vision that is sufficient for use as a primary learning channel for reading, writing and other school activities. Fifty to sixty percent of school-age individuals with vision impairments have additional impairments. Forty percent of persons with cerebral palsy have concurrent visual problems.
Three stages of vision include: sight, which is the reception of sensory stimulation through the eye, transmission of the image along the optic nerve and interpretation of the image in the visual cortex of the brain where information is transformed into meaningful information. Visuals problems can include problems with visual acuity, visual field, oculomotor functioning, light sensitivity, glare sensitivity, color perceptual problems and visual stability. Problems in any of these areas need to be considered when deciding which accessing system to use and what type of symbols will be used.
AAC users need to begin development of auditory scanning skills as soon as possible and in the most optimum way. Instead of looking at specific devices and the ways that they support auditory scanning skills, you will need to look at the vocabulary needs of the individual. Determine the most mathematically efficient way the user can access the vocabulary. The purpose of the vocabulary and the environments in which it is used may dictate the most efficient navigational strategies.
Start with live voice scanning first. The assistant names the choices, the person signals for the appropriate response. This is much like 20 questions and has two problems. It is limited to whatever thoughts occur to the partner and it uses linear scanning. One thing is presented at a time.
In linear scanning, you will want to start with two items and then advance to three and then more items. Add stringing when the client is beginning to learn the rules that govern word order. At this point the person is beginning to acquire literacy skills.
Group-item scanning requires the person to learn categories.
Most individuals will require training and repetition. When they learn the first 2-3 categories, more categories can be added. This is more difficult. After a category is selected, linear choices from within that category are presented. For example our categories are the four food groups, meats, fruits and vegetables, dairy, bread and grains. The person chooses fruits and vegetables. Now they hear a list of fruits and vegetables and can choose the one they wanted.
It is possible to present letters using group-item scanning by presenting
The person picks a through g and then the choices are presented:
A B C D E F G
Using this technique, the person can communicate by spelling and creating novel messages.
The different ways of presenting auditory scanning can include live voice or aided scanning as discussed earlier. When using electronic devices, there are several ways that the messages can be presented.
In the "no repeat" situation, items are listed, usually linearly, and the person signals when they have heard the item that they would like to select. The scanning stops and the communication partner must remember the last item listed because that is the choice that has been made.
In the "repeat" situation, the items are listed, the person signals when they have heard the item to select and then that item is repeated. This is much easier on the communication partner and it gives the person who is scanning a chance to check their response to see if it is what they really wanted.
A "cue" can be used in "repeat" auditory scanning. Instead of scanning through entire messages only one or two words are given as a cue. For example: when scanning through a list of fruits, the auditory scan might consist of: apple, banana, cherries (etc). The person signals when they hear the word cherries. The device would then say a complete sentence like "I want to buy cherries at the store this week". This method saves time in listening to the choices and presents a complete thought when selected.
Another way that some electronic devices allow for auditory scanning involves the use of earphones or a pillow speaker. In this case, when the items are being presented, the person doing the scanning wears the earphones or has the pillow speaker placed close to their ear. They listen to the choices privately. After they make their selection, the message is spoken through a speaker that the communication partner can hear. The negative aspect to this is that the person could be sitting there for a long time listening to choices and the partner doesn't really know what they are doing. They could be listening to choices or they could just be sitting there. If you are working with a person who needs much reinforcement to continue, you might want to hear the choices as they are hearing them.
To work with a person who needs to use auditory scanning, many aspects of that person must be considered. We have looked at their ability to make decisions, switch access, vision and the various ways that auditory scanning can be accomplished.
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Zabala, Joy (1995) The SETT Framework: Critical Areas to Consider When Making Informed Assistive Technology Decisions. Houston TX: Region IV Education Service Center.
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