Line Harp: Importance-Driven Sonification for Dense Line Charts

Accessibility in visualization is an important yet challenging topic. Sonification, in particular, is a valuable yet underutilized technique that can enhance accessibility for people with low vision. However, the lower bandwidth of the auditory channel makes it difficult to fully convey dense visualizations. For this reason, interactivity is key in making full use of its potential. In this paper, we present a novel approach for the sonification of dense line charts. We utilize the metaphor of a string instrument, where individual line segments can be “plucked”. We propose an importance-driven approach which encodes the directionality of line segments using frequency and dynamically scales amplitude for improved density perception. We discuss the potential of our approach based on a set of examples.

💡 Research Summary

The paper introduces “Line Harp,” an interactive sonification technique designed to make dense line charts accessible to users with low vision or blindness. Building on the metaphor of plucking a string on a harp, the system generates a musical note each time the mouse cursor intersects a line segment. Two core mappings drive the audio: the direction of a segment is encoded as pitch (frequency), while a pre‑computed importance value for each segment controls loudness (amplitude). Importance is defined by a scalar function β(u)∈