Instructors often use text-based methods when giving feedback to students on their papers. With the development of audio recording technologies, audio feedback has become an increasingly popular alternative to written feedback. This study analyzed five instructors' commenting patterns of both written and audio feedback. The five instructors, who taught sections of the same undergraduate composition class, provided written feedback to students on one writing assignment and audio feedback on another writing assignment. A mixed-methods research methodology was employed for the study. Data were collected through surveys, students' writing assignments, digital audio files (for audio feedback), and interviews. The findings indicated that the word count and the number of items commented on differed between audio and written commentary. In addition, there was a teacher effect and an interaction effect for both word count and number of items in the instructor feedback. The interview data offered explanations for why the teacher effect and the interaction effect might have occurred. The findings show that an individual teacher's commenting styles and strategies, as well as the medium used in commenting, have a strong influence on the nature and length of the commentary. Implications for future research and practices were discussed at the end of the paper.