<p>It is common for learners to listen to background music during learning activities. However, existing research has produced inconclusive results on the effects of background music on learning due to different circumstances and contexts. There is a lack of detailed understanding regarding the effects of various background music properties on learning. Based on the arousal-and-mood hypothesis, this study investigates how background music with different tempi (fast and slow) and modes (major and minor) affects reading comprehension through the mediation of learning emotions. A within-subject research was conducted with 33 graduate students who listened to five pieces of background audio while completing reading comprehension tasks. Particularly, a multimodal approach was adopted to capture participants’ emotions through self-report scales, facial expression recognition, and physiological monitoring. Using a series of linear mixed models for data analysis, results demonstrated that background music with different tempi and modes were associated with significantly different self-report emotion measures, facial expressions, and physiological responses. Moreover, while music properties did not directly predict reading comprehension performance, music-induced emotions measured by self-reported valence, body temperature, and heart rate were significantly associated with reading comprehension performance. Therefore, this study establishes through multimodal emotion measures that background music properties have indirect effects on reading comprehension performance through the mediation of music-induced emotions. This study refines the current understanding of background music and contributes to the music selection and design for learning.</p>