Competence in written scientific communication is an important learning outcome of undergraduate science degrees. Writing helps students learn, encourages them to think creatively and critically about their learning, and trains them in communicating their insights as disciplinary experts. However, challenges exist in incorporating writing assignments into large undergraduate science classes, including lack of student engagement and difficulty in providing effective and personalized formative feedback to large numbers of students. Engagement and feedback are especially important for developing writing skills, which require active, reflective, critical attention on the learner's part: it would be very useful if one mechanism could enhance both. We recently integrated audio feedback into the stages of a term-long, multi-part scientific literacy assignment in a large undergraduate biology class at the University of Toronto Mississauga, using it for formative purposes at early stages of the assignment. In order to determine the utility and effect of the audio feedback, we collected data from both teaching assistants (TAs) and students. In general, students felt audio feedback was constructive and engaging, and both TAs and students commented that audio feedback was more personal than written feedback. However, TAs noted that it took longer for them to give audio feedback compared with written feedback, and that they encountered technical issues with emailing audio feedback to the students. Overall, the response to audio feedback from both students and TAs suggested that this approach is logistically feasible and might aid in overcoming the disengagement that is often found in large introductory courses.