Speaking out for speakers: a guide for and analysis of robot speaker design

Despite sound being a promising modality of communication in robotics (possessing, for example, the ability to improve people's perceptions of robots and help localize robotic systems in space), its facilitator, speakers, are a seldom-explored topic of study in robotics literature. To address this gap, we conducted three explorations into physical speaker design that identified what current robot speakers lack and potential remedies, low-level design improvements, and post hoc hardware additions. Further, we detail and explore the application of speakers on three different robotic platforms (including one industrial robot used for construction), the last evaluation of which involved an empirical study $\left(N=21\right)$ that sought to better understand the implications associated with poor-quality speakers in a mock service robotics context. Our results suggest that greater internal cavity volume is a key strength in speaker design. We also observed greater effects of the presence (vs. absence) of a service robot voice compared to other factors. This work can inform the process of creating custom speakers for robots and augmenting current robotic systems with new speaker additions (whether commercial or custom, and across use contexts from construction to service). In particular, the work can help to guide roboticists who may be unfamiliar with nuanced audio engineering techniques and designers who seek to improve robotics platform standards with human interlocutors in mind.