People often include screen reader users in the much larger group of keyboard-only users. Whilst this is correct (most screen reader users don’t use a mouse), it also creates a false impression of the way screen reader users navigate content.
The aria-roledescription attribute changes the way screen readers announce the role of an element. Intended to give authors a way to provide a localised and human-readable description for a role, it has the capacity to both enhance and seriously break accessibility for screen reader users.
The accessible SVG line graphs post explains how to use ARIA table semantics to make that form of data visualisation accessible to screen readers. This article uses the same ARIA based approach to make a screen reader accessible SVG flowchart.
SVG is often used for data visualisation, but because SVG lacks the semantics to express structures like bar charts, line graphs, and scatter plots, the content is difficult for screen reader users to interpret. The solution is to use the technique for creating accessible SVG tables as your starting point.
SVG has no native semantics for representing structures like tables, but ARIA1.1 introduces a number of roles that can be used to polyfill the necessary semantic information.