Explore the intricacies of designing effective voice interfaces in this 49-minute conference talk from CSS Day 2023. Delve into voice character and design, conversational user experience, and APIs for generating synthetic speech both in-browser and cloud-based. Discover techniques for manipulating voice output, including an introduction to an often-overlooked CSS module. Learn why voices are crucial in interface design, drawing parallels with Hollywood's understanding of voice importance. Examine synthetic speech, SSML, and CSS speech properties, understanding their significance and potential use cases. Investigate design outcomes, semantics, UI patterns, and the role of emojis in voice interfaces. Gain insights into the challenges of implementing CSS speech and Google's approach to voice reading. Join Léonie Watson as she shares her expertise on this emerging aspect of web design, offering practical knowledge for creating more accessible and engaging voice-driven experiences.