This study investigated students' and instructors' approaches and preferences to audio and written comments in an online undergraduate composition class. A mixed-method design was employed utilizing both a survey instrument and interviews for data collection. Forty-nine students and five instructors participated. Students gave more positive ratings to audio comments than to written comments on global- and middle-level items. However, their impressions on the comprehensibility of audio and written comments at the micro level were mixed. Instructors showed a preference for audio comments over written comments in terms of time investment. In addition, instructor commenting styles and the medium used influenced the time invested in providing comments