Previous studies have shown that human senses interact with each other. In this study, an experiment was conducted in a dining space to find methods for improving the indoor sound environment through audio-visual interaction. Differences among diners' conversation behaviours were collected on the basis of acoustic measurements before and after displaying visual media content. Acoustic perception and feelings of the diners were analysed through a survey questionnaire. Four types of content (different, dynamic, transformation, foci), three positions (front, corner, side), and three brightness levels (bright, moderate, dark) were compared. It was found that displaying visual media content reduced the sound pressure level by 2.1 dB in 10 s. Furthermore, playing media content attracted people's attention and reduced 2% of the total conversation duration among 12% of the diners, indirectly improving the acoustic environment. Last, results of the administered questionnaire show that diners' acoustic comfort and subjective perception of loudness improved within 0.53 points after media playback.