“Hello, This Is a Voice Assistant Calling”: When a Human Voice Calls Claiming to Be a Machine on an Ordinary Day

With the advent of neural networks, it has become possible to generate synthetic voices that are nearly indistinguishable from real human speech (i.e., human-sounding voice).In contrast, earlier voice assistants used voices that were instantly recognizable as machine-generated, owing to their standardized, consistent, and highly intelligible qualities (i.e., artificial-sounding voice).Although people tend to prefer human-like voices, adopting human-sounding voices in voice assistants raises ethical concerns related to confusion or unintentional deception, particularly in voice-only contexts, even when their identity as systems is explicitly disclosed.To explore the voice design direction for future voice assistants, we examined how participants perceived and interacted when they were unexpectedly confronted with either an artificial-sounding or a human-sounding voice, both of which clearly identified themselves as voice assistants during an everyday phone call.Our findings reveal participants' experiences and conversational behaviors in each voice condition.Furthermore, we discuss how the voices of voice assistants should be designed and propose design implications that emphasize transparency and responsiveness in voice design.