Apple is seeking Machine Learning Engineers for the Siri Attention & Invocation team to enable personalized Siri interactions globally. Responsibilities include building end-to-end model training and evaluation pipelines, advancing research in speaker recognition, and deploying on-device models that align with Apple's core values of quality, innovation, and user privacy. The role involves collaborating with cross-functional teams of software and machine learning engineers to improve Siri's understanding, personalization, and interaction capabilities. The team owns user journeys end-to-end, measuring model impact on production traffic and optimizing error rates, while also defining new user experience-focused metrics and addressing on-device computation constraints.