In order to have an audio graph of data, it is important to first set the plot range in the Plot tab page and then calculate a function or otherwise input a data set in one of the two Data Set tab pages. When a data set is calculated, or the data set is updated with the F4 key, a new graph is generated. After the graph is generated, it can be played from the Wave tab page or by pressing the F5 hot key.
The Wave tab page contains controls for audio plotting features. There are five main control sections: Volume, Y Threshold, Play time, Wave Type, and Frequency Range. At the bottom of the page are buttons controlling the playing of the sound graph.
The Volume section contains a volume slider options for the volume of the Data set sound. The slider can be moved with the arrow keys in increments of 5%. Also in this section is a check box for Y (vertical) axis tick marks. Checking the box turns on the tick mark sound. The tick marks are auditory cues, represented by clicks during playback, that help with the determination of the slope of a graph. The greater the slope, the more frequent the clicks. The pitch of the tick marks gives an indication of the graph's curvature (second derivative). Clicks have a high pitch if the graph has positive curvature (positive second derivative) and a lower pitch if the graph has negative curvature at the time the tick mark is heard.
There is also a slider to control the volume of the tick marks in relation to that of the Data. The sum of the Data and Tick volumes can not be greater than 100%. If one slider volume is adjusted so that the sum would be greater than 100%, the other slider is automatically reduced to bring the sum to 100%.
The Y Threshold section contains a check box that turns on and off the "negative" sound. When data are played that are below the Threshold level, a white noise sound similar to static on an unused television channel is heard in conjunction with the data sound. This alerts the listener that the data is "negative" relative to the threshold value. The threshold value can be changed in the entry box in this section. The default values are 0 for the level and on for the check box.
The Play time section contains a slider that sets the length in seconds of the generated sound graph. The play time for the auditory graph can range from 1 to 30 seconds. The Play time also determines the time when generating a .wav file.
The section for Wave Type contains choices for either Monophonic or Stereo output. If Stereo output is selected, the sound will pan from the left (minimum x) to the right (maximum x) speaker when the graph is played. If saving the auditory graph to a file, choosing Mono output will produce a smaller file.
The section for Frequency Range contains two sliders that control the minimum and maximum frequencies that the auditory graph will span. These ranges can be set to match a user's sensitivity or preference. The Minimum frequency has a range of 40 to 500 Hertz, while the Maximum frequency has a range of 500 to 4000 Hertz.
At the bottom of the page are six buttons for sighted users that control playback of the wave file. There are equivalent hot-keys of all the buttons for people who don't want to, or can't, use the mouse. The play button is F5, Stop is the ESC key, Next and Back are ALT RIGHT and LEFT ARROW respectively, Home is ALT HOME, and End is ALT END. A summary of the hot keys is given in the Hot Keys page.
The audio plots may be saved in a .wav file format. This is useful if you would like to save an audio plot to use in another application or for future reference. Once you have an auditory graph that you want to keep, use the Graph menu and choose Write Wave File (ALT G, W) or use the F6 hot key. A save dialog box appears so you can enter the filename and directory to save the auditory graph in.
The default file location is the directory where the TRIANGLE Calculator is located. On most systems this is C:\Program Files\TRIANGLE Calculator\. This directory can be changed by TABbing to the Drive and Directory lists, and then choosing the desired drive or directory.
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Questions about the Accessible Graphing Calculator? Problems with the download? Send e-mail to: triangle@dots.physics.orst.edu
The Accessible Graphing Calculator was written by the Science Access Project at Oregon State University. It is Copyrighted and all rights are reserved.
Last modified February 14, 2000.