How do you add voice, music, and sound design to an AI-generated short film?

Build the audio in three layers in this order: dialogue and voiceover first, sound design and ambience second, music last. Generate each layer with a specialist AI tool (ElevenLabs for voice and SFX, Suno or Udio for score), then assemble and mix inside the invideo editor or a DAW/NLE against your locked picture.

Start with the picture locked. Audio decisions — line readings, cue placement, score length — only stabilize once your edit no longer moves, so finish your AI video cut before generating a single audio asset.

1. Dialogue and voiceover (the top layer). Write each line out and generate it in ElevenLabs using a voice cloned or selected per character; use the voice settings to push tone, emotion, and pacing (lower stability for more expressive reads, higher for narration). Generate two or three takes per line, drop them onto the timeline against the character's on-screen mouth, and pick the take that sits closest to the picture. For talking-head shots where the AI-generated face has visible lip movement, run a lip-sync pass — Hedra or a lip-sync model routed through the invideo agent will retime the mouth to the audio. invideo also has a native voiceover stack with a large AI voice library you can generate straight onto the timeline, which collapses the export/import step when you're working end-to-end on one platform.

2. Sound design and ambience (the middle layer). This is the layer most AI films miss, and it's what makes the picture feel real. Work in two passes. First, lay a continuous ambient bed under every scene — room tone for interiors, wind/traffic/forest for exteriors — so you never have true silence between lines; generate these as 30-60 second loops in ElevenLabs Sound Effects (prompt like "quiet office room tone, distant HVAC hum") or pull from Freesound. Second, spot specific effects to picture: footsteps, doors, props, impacts, whooshes on camera moves. Prompt the SFX model with the physical material and action ("hard plastic toy hitting wooden floor, single impact") — the diegetic-sound logic the invideo agent uses when briefing visual assets carries straight into sound effect prompts. Place each effect on the frame the action lands.

3. Music (the bottom layer). Generate score in Suno or Udio by prompting genre, instrumentation, tempo, and mood ("slow piano, minor key, sparse strings, 70 BPM, melancholic"). The known limitation: these models don't compose to picture, so they won't hit your cut points. Two workarounds — generate a track longer than your scene and edit the picture or the music to land hits on cuts, or generate multiple short variations (intro, build, resolve) and stitch them in your timeline. Keep music under the dialogue by 10-15 dB; it should support, not compete.

One orientation note: invideo is an agentic video creation platform with the current video and image models built in, plus native voiceover, music, and SFX inside the editor — so the same project that generated your video can layer audio on the same timeline without round-tripping through a separate tool. You can also spin up a sub-agent named something like "sound designer" and have it walk the cut shot by shot suggesting SFX prompts and ambient beds, the same way a creative producer agent holds script context for video.

Mix and deliver. Once all three layers are on the timeline, balance them: dialogue at -12 to -6 dB, SFX -18 to -10 dB, music -24 to -18 dB under speech (duck music 6-8 dB whenever a line plays). Mix inside invideo, or export stems and finish in DaVinci Resolve's Fairlight page. Master the final mix to -14 LUFS for online delivery.

These are the layers and tools that work today — your exact stack will depend on whether you're delivering a talking-head piece (lip-sync matters most), a cinematic short (sound design and score carry the weight), or a commercial (voiceover and music sync to beats).

Hard material, so it makes a horrible sound when it falls.

— Hridaye, invideo's creative director — on encoding diegetic sound logic directly into asset briefs, the same prompting posture that translates to SFX generation