New Orientation and Accessibility Option for Persons with Visual Impairments: Transportation Applications for Remote Infrared Audible Signage.
Short title: Infrared signage for blind travelers.
William Crandall, Ph.D.1; Billie Louise Bentzen, Ph.D.2; Linda Myers, M.Ed.3; John Brabyn, Ph.D.1
1The Smith-Kettlewell Eye Research Institute, 2Accessible Design for the Blind, 3Marin County Office of Education
This material is based upon work supported by the National Institute on Disability and Rehabilitation Research, Project ACTION of the National Easter Seal Society (with support from US Department of Transportation and the Federal Transit Administration), and from The Smith-Kettlewell Eye Research Institute. Assistance was provided by the Bay Area Rapid Transit (BART), the San Francisco Municipal Railroad (Muni), and the San Francisco Department of Parking and Traffic.
Address all correspondence and requests for reprints to: William Crandall, Ph.D., Rehabilitation Engineering Research Center, Smith-Kettlewell Eye Research Institute, 2318 Fillmore Street, San Francisco, CA. 94115 Tel. 415-345-2111 V 415-345-8455 Or email: bc@ski.org. http//www.ski.org/rehab/wcrandall
ABSTRACT
Background: For a blind or visually impaired person, a vital prerequisite to accessing any feature of the built environment is being able to find this feature in the first place. Braille signs, even where available, do not replace the functions of print signage because they cannot be read from a distance. Remotely readable infrared signs utilizes spoken infrared message transmissions to label key environmental features so that a blind person with a suitable receiver can locate and identify them from a distance.
Methods: Three problems that are among the most challenging and dangerous faced by blind travelers are: negotiating complex transit stations, locating bus stops, and safely and efficiently crossing light controlled intersections. We report the results of human factors studies using a remote infrared audible sign system (RIAS), Talking SignsR, in these critical tasks, examining issues such as the amount of training needed to use the system, its impact on performance and safety, benefits for different population subgroups and user opinions of its value.
Results: Results are presented in the form of both objective performance measures and in subjects’ ratings of the usefulness of the system in performing these tasks. Findings are that blind people can quickly and easily learn to use remote infrared audible signage effectively, and that its use improves travel safety, efficiency and independence.
Conclusions: The technology provides equal access to a wide variety of public facilities.
Key Words: Remote, Infrared, Audible, Signs, Labeling, Accessible, Wayfinding, Orientation, Talking Signs
INTRODUCTION
Blindness affects approximately 45 million people world wide. Because of aging and population growth, this number is expected to double by the year 2020 (1).
Safe and independent travel for blind and visually impaired persons is made especially difficult by lack of access to the signs and landmarks the rest of the population takes for granted. Braille signs, even where available, do not replace the functions of print signage because they cannot be read from a distance; they have to be searched for and found before the information they contain can be used; and a majority of people who are unable to read print signs (because of visual limitations) have not learned to read Braille. Solutions for this problem may help other populations as well, such as those who cannot read or for some other reason prefer auditory information, and those who would benefit from verbal reinforcement or redundancy (such as persons with developmental disabilities).
Currently, persons with severe visual impairments most often require extensive assistance from strangers in order to travel in unfamiliar areas. In the best case, the information they receive is accurate, concise, and in the appropriate language. Such an ideal source of information is seldom available. In urban areas, persons who are blind may have safety concerns about approaching strangers for assistance. Finally, blind people just do not like to be dependent upon others for information -- especially if there are suitable alternatives.
The concept of remotely readable infrared signage (2) is to level the playing field for those unable to use printed signs. For example, the Talking SignsR system (3), developed at the Smith-Kettlewell Eye Research Institute, uses infrared transmitters placed at sign locations or on key environmental features. Transmitters send out a spoken message on a beam of infrared light. The prerecorded human speech frequency modulates (FM) a 25 kilohertz carrier. The blind user carries a receiver (a small hand-held box containing photodetector, FM discriminator, amplifier, and internal speaker) which, when activated by a push button, translates the message back into spoken language. Users hear the digitally recorded message whenever the front of the receiver is pointed in the direction of the infrared transmitter. The beam starts out at the infrared diode and spreads out in a cone-like fashion, becoming wider as it moves away from the source. Adjustment of the transmitters and the LED arrays ("tuning" of the system) allows control of the maximum distance at which the Talking Sign message is received, the direction in which a message is transmitted, and the area the message covers. The directional selectivity is a characteristic of the analog FM transmission over an infrared beam; the intensity and clarity of the message increases as the sign is "pointed at" or approached. This ensures that the people using the Talking SignsR system can choose to get feedback about their relative location to the goal as they move towards it.
Figure 1. The Talking Signs system comprise infrared transmitters in the environment which provide information to users by way of a hand held receiver. The directional characteristics of the infrared beam ensures precise “point-out-ability” of the sign’s location. Frequency modulated transmission of the infrared messages allow multiple transmitters to be in close proximity without cross interference.
Since inception, the system has undergone continuous refinement and adaptation to a wide variety of signage applications. Various human factors studies have examined such issues as training needs (3), speech intelligibility (4), receiver beamwidth (5), comparison with other technologies (6), safety, precision, accuracy, and how best to use the technology in controlled intersections and underground transit stations (7).
People who have print reading disabilities unrelated to visual impairments also benefit from this technology. Results show that persons with cognitive impairments effectively use the verbal information which Talking Signs provides when they were tested for travel ability in a transit station (8).
Within the past 5 years, approximately 1000 Talking Signs units have been installed in San Francisco. Talking Signs are also located in nine other cities in the US as well as in four other countries.
The present paper reviews the impact of remote infrared signage on accomplishing tasks routinely encountered by people in transit related activities while navigating a complex underground transit station, locating bus stops, and negotiating signal controlled street crossings. Results are presented in the form of both objective performance measures and in subjects’ subjective ratings of the usefulness of the system. The results point to a seamless infrared signage environment where a visually impaired traveler could: walk safely across an intersection to an ATM or fare machine; from fare machine to bus stop; from bus stop to bus; from bus to building; from building to elevator; from elevator to office; from office to restroom, etc.
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