External Human-Machine Interfaces (eHMIs) have been proposed to facilitate communication between Automated Vehicles (AVs) and pedestrians. However, no attention was given to Deaf and Hard-of-Hearing (DHH) people. We conducted a formative study through focus groups with 6 DHH people and 6 key stakeholders (including researchers, assistive technologists, and automotive interface designers) to compare proposed eHMIs and extract key design requirements. Subsequently, we investigated the effects of visual and auditory eHMI in a virtual reality user study with 32 participants (16 DHH). Results from our scenario suggesting that (1) DHH participants spent more time looking at the AV; (2) both visual and auditory eHMIs enhanced trust, usefulness, and perceived safety; and (3) only visual eHMIs reduced the time to step into the road, time looking at the AV, gaze time, and percentage looking at active visual eHMI components. Lastly, we provided five practical implications for making eHMI inclusive of DHH people.

翻译：外部人机界面（eHMIs）已被提出用于促进自动驾驶车辆（AVs）与行人之间的通信。然而，目前尚未关注聋人与听力障碍者（DHH）的需求。我们通过焦点小组开展了一项形成性研究，邀请6名DHH人士和6名关键利益相关者（包括研究人员、辅助技术专家和汽车界面设计师），比较现有eHMI提案并提取关键设计要求。随后，我们在虚拟现实用户研究中调查了视觉与听觉eHMI的效果，共有32名参与者（其中16名为DHH）。研究场景的结果表明：（1）DHH参与者注视自动驾驶车辆的时间更长；（2）视觉与听觉eHMI均能提升信任度、实用性和感知安全性；（3）仅视觉eHMI能减少步入道路的时间、注视自动驾驶车辆的时间、凝视时间以及注视动态视觉eHMI组件的百分比。最后，我们提出了五项实践建议，以使eHMI设计能包容DHH人群。