In comparison to instructional videos, the role of audio-only instructional content in online learning has received scant attention. When audio-only content is discussed, the research often centers on the use of audio feedback or student-created podcasts, rather than instructor-created instructional audio. Additionally, few studies have compared learning outcomes from recorded video lectures versus from audio alone, except within the context of specific disciplines, such as second language acquisition (Berner & Adams, 2004).