Chart Sonifier

Nothing makes a sound until someone presses Play or moves the slider — the audio context is only created then — and Pause, Escape from anywhere in the group, and Mute silence it at once, with a fade too short to hear. Everything the sound conveys is also text: a one-sentence summary of the chosen series (range, overall trend, highest and lowest points) describes the group, and the slider's aria-valuetext reads "Tue 14 Oct: 42 deployments" for each point. Arrow keys step a point, Page keys a tenth, Home and End go to the ends, and each step plays that point's note unless muted. While playing, the thumb follows the playhead but the announced value holds still, so a screen reader does not talk over the notes; on pause the new position is announced once through a status region ("Paused at …"), unless the slider has focus and announces it itself. Play is named for what it will do (Play or Pause); Mute is a toggle button with aria-pressed; speed is a native radio group and the series a native select. Where the Web Audio API is missing, Play is disabled and says why, and the slider still reads every value.