Synesthesia is a phenomenon where one sense can trigger a secondary experience in another sense. In the context of sound design or film composition, synesthesia can refer to the practice of using sound and music to evoke non-auditory sensations, such as colors, textures, or emotions.
We like to explore the usage of sound for synesthsia purpose, from the easier example of using low-frequency rumble for tension or using high-pitch for shinning sparkles or bright colours.
Another example is that in some film or animation works, people's brains are still active at the moment when they lack the content at the visual level. In such moments, a suitable music and audio design can act like a trigger to activate people's imagination and senses, making the work perfect.