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Audio Trace

Updated

Audio trace is a powerful accessibility feature that anyone can use to explore a single equation or an entire system of equations through sound. 

Audio Trace Mode

To open Audio Trace Mode, press Alt + T (Windows) or Option + T (Mac) while focused in an expression line or the graph. Alternatively, open the keypad and click the sound icon.

Hear Graph

Press H or click Hear Graph to listen to your equation.

In headphones or on stereo speakers, the sound of the graph will move from left to right as the trace point moves in the same direction. A static effect plays when the \(y\) values are negative, and timbre (or quality) of the tone increases when the \(x\) values are positive. In graphs that use \(x\) as the dependent variable, the cues flip.

You can change the volume and speed of playback:

  • To increase volume, press
    V
  • To decrease volume, press
    Shift
    +
    V
  • To change the speed, press
    Alt
    +
    1
    for the slowest playback or
    Alt
    +
    0
    for the fastest playback. Or, use any number from 2–9 for an intermediate speed.

    • Equation: \(y=x\)

    Notice how the pitch increases as the equation moves from left to right. This increase indicates a positive slope. The audio starts with static when the \(y\) values are negative and clears once the \(y\) values become positive.

    Equation: \(y=-x\)

    Notice how the pitch decreases as the equation moves from left to right. This decrease indicates a negative slope. The audio starts without static, but the static begins once the \(y\) values become negative.

    Equation: \(y=\sin x\)

    Notice how the pitch regularly increases and decreases as the equation moves from left to right. This fluctuation indicates a periodic function. The static plays when the \(y\) values are negative, and the timbre increases when the \(x\) values are positive.

    Equation: \(y=x^{2}\)

    Notice how the pitch starts high, drops down, and then rises as it moves from left to right. The pitch rises and timbre increases when the \(x\) values are positive.

    Equation: \(x^{2}+y^{2}=9\)

    For this equation, the bottom half of the circle first plays from left to right. The sound has static, and the pitch moves down and then up. Then, the top half of the circle plays left to right without any static, and the pitch moves up and then down.

    Equations: \(f\left(x\right)=-2x+4\) and \(g\left(x\right)=x^{2}+1\)

    This video traces \(f(x)\). The pitch decreases, which indicates a negative slope. We also hear two pops, which occur when \(f(x)\) intersects \(g(x)\).

    Navigation and Screen Readers

    Under Navigation, you can move between different points and curves.

    While using audio trace, a point will appear on your graph by default. Press Left Arrow or Right Arrow or the on-screen buttons to move the point.

    Some graphs also have points of interest, which include intercepts or intersections between multiple equations. Press Tab to jump to the next point of interest or Shift + Tab to return to the previous one.

    If a graph includes multiple curves, press Alt + Down Arrow (Windows) or Option + Down Arrow (Mac) to move to the next entry in the expression list. To move back, press Alt + Up Arrow or Option + Up Arrow.

    If the graph is attached to a slider, press S to connect the slider to arrow keys. For example, if the slider starts at \(b=1\), press S and then Left Arrow twice to move to \(b=-1\). Press H to play the updated graph.

    If you are using a screen reader, you can hear a description of points, curves, and axes:

    • To hear a description of points, press T
    • To hear a description of curves, press Alt+ S (Windows ) or Opt+ S (Mac)
    • To hear a description of the axes, press Alt+ G (Windows ) or Opt+ G (Mac)

    For more details on setting up a screen reader, visit our Accessibility page.

    Learn More

    Please reach out to us with any questions or suggestions to support@desmos.com or accessibility@desmos.com.