  We present Umwelt, an authoring environment for interactive multimodal data
representations. In contrast to prior approaches, which center the visual
modality, Umwelt treats visualization, sonification, and textual description as
coequal representations: they are all derived from a shared abstract data
model, such that no modality is prioritized over the others. To simplify
specification, Umwelt evaluates a set of heuristics to generate default
multimodal representations that express a dataset's functional relationships.
To support smoothly moving between representations, Umwelt maintains a shared
query predicated that is reified across all modalities -- for instance,
navigating the textual description also highlights the visualization and
filters the sonification. In a study with 5 blind / low-vision expert users, we
found that Umwelt's multimodal representations afforded complementary overview
and detailed perspectives on a dataset, allowing participants to fluidly shift
between task- and representation-oriented ways of thinking.
