Auditory menus are not just spoken visual menus: a case study of "unavailable" menu items

Auditory menus can supplement or replace visual menus to enhance usability and accessibility. Despite the rapid increase of research on auditory displays, more is still needed to optimize the auditory-specific aspects of these implementations. In particular, there are several menu attributes and features that are often displayed visually, but that are not or poorly conveyed in the auditory version of the menu. Here, we report on two studies aimed at determining how best to render the important concept of an unavailable menu item. In Study 1, 23 undergraduates navigated a Microsoft Word-like auditory menu with a mix of available and unavailable items. For unavailable items, using whisper was favored over attenuated voice or saying "unavailable". In Study 2, 26 undergraduates navigated a novel auditory menu. With practice, whispering unavailable items was more effective than skipping unavailable items. Results are discussed in terms of acoustic theory and cognitive menu selection theory.