Sound design is the creative discipline of crafting, selecting, editing, and mixing all non-music audio elements in a production, including dialogue, ambient sound, sound effects, foley (recreated everyday sounds), and atmospheric audio layers. It is one of the most powerful tools for shaping how an audience experiences a scene, with the emotional and perceptual impact of sound often rivaling or exceeding that of the visual content.

Effective sound design creates a sense of physical space and presence that purely visual content cannot achieve on its own, grounding the viewer in the reality of a scene through the subtle accumulation of environmental audio - the distant sound of traffic, the texture of a room's acoustic ambience, the specific sound of footsteps on different surfaces. Beyond realism, sound design is used expressively to heighten tension, signal subjectivity (hearing a character's internal state through distorted or heightened audio), create contrast between image and sound for deliberate effect, or establish the sonic identity of a world or genre. The discipline requires deep collaboration between the sound designer, director, and picture editor to ensure that audio and visual elements work together as a unified creative statement.

In AI video production workflows, sound design is typically addressed in post-production after the visual content is assembled. While some AI video models now generate basic synchronized audio alongside video, most professional sound design work happens separately, with generated or recorded audio elements layered and mixed against the completed visual edit to create the final audiovisual experience.