How to add AI sound effects to any video
Most videos don't need music. They need sound. A door closing. A glass setting down. A car pulling away off-screen. Sound effects do more for perceived production value than any color grade, and they're the first thing creators skip because sourcing them is annoying.
AI sound effect generation fixes the sourcing problem. You describe a sound, you get a sound. The harder problem is placement: when, where, and how loud. The hardest problem, the one most tools ignore, is knowing what sounds the video actually needs in the first place.
This piece walks through the whole loop: generation, placement, the agentic shortcut that automates both, and a practical workflow for a 60-second video.
Why sound effects matter more than music
Walk through any well-edited piece of video and mute the music. The cuts still feel intentional. The actions still land. Now mute the sound effects too. The whole thing collapses into something amateur.
Music sets mood. Sound effects make a video feel real. The tradition behind this work is called foley, named for sound editor Jack Foley, and film has relied on it for nearly a century. A 60-second product video with three well-placed effects (a click, a whoosh on a transition, a soft thud when text lands) reads as professional. The same video with a stock music bed and no sound effects reads as a slideshow with audio.
The trade is unfair. Music is expensive to license, easy to add. Sound effects are cheap to source, hard to place. Most creators do the easy thing.
Generating the effect
Modern AI sound systems take a text prompt and return a clip in 3 to 10 seconds. Quality varies by category.
Foley-style organic sounds are usually convincing. Footsteps, doors, fabric, kitchen sounds, weather. The models have seen enough of these that the output feels physical.
Mechanical and synthetic sounds can land flat. Engines, machinery, sci-fi UI bleeps. The models tend toward generic. Always generate three or four variations and pick the one that doesn't sound canned.
Prompt structure matters more than people expect. "Door closing" gets you something generic. "Heavy wooden door closing softly, indoor reverb, no latch click" gets you something usable. Specify material, motion, environment, and what you don't want.
Placing it without making the video worse
Three rules.
Sync to the visible action. If a hand sets a cup down at 00:04.21, the clink lands at 00:04.21, not 00:04.18 and not 00:04.30. Off-sync foley reads as broken before the viewer can tell why. The brain processes audio-visual sync at frame-level precision. You don't get to be close.
Duck the music. Sound effects fight background music for the same frequency space. Drop the music 6 to 8 dB under the effect for the duration of the hit, then ramp back. Without ducking, the effect either disappears under the music or punches through too hard.
Leave headroom. A sound effect at full volume will dominate a mix tuned for dialogue. Aim for 6 to 12 dB below the loudest dialogue peak. The goal is for the viewer to feel the sound, not consciously notice it.
The agentic shortcut: scene reading, sound selection, and sync as one operation
The manual workflow described above is what a careful editor does. An agentic video editing system does it automatically.
Here's what that means concretely. The system watches the video the way a human would. It reads each scene, identifies the visible actions ("door closing," "cup setting down on wood," "footsteps on gravel"), decides which actions warrant a sound effect, picks or generates the right sound for each, and times the hit to the exact frame the action lands on. Music ducking and headroom adjustments happen in the same pass.
You don't write prompts. You don't mark timestamps. You don't generate four variations and pick one. The system does the scene analysis, the sound selection, and the placement in a single coordinated step, and hands you a finished mix to review.
This is the part most "AI sound effect tools" miss. They generate sounds well. They don't understand what's happening on screen, so they can't decide what sounds belong or where. An agentic editor closes that loop because it routes between models: a vision model for scene understanding, a generation model for the sound itself, a deterministic engine for sync and mixing. No single model can do all of that. A coordination layer can. We made the broader case for this architecture in a separate piece.
Where Poolday fits
Poolday is built around this loop. The editing system reads the cut, identifies actions worth scoring, generates or retrieves the right sounds, times them to the visible action, and adjusts the music bed automatically. You review the result and approve, the same way you'd review a junior editor's pass.
In autonomy ratio terms, sound design on a typical 60-second video runs at 100% on the execution side. The creative call (which moments deserve a sound, what register the mix should sit in) stays with you. The clicks don't.
A practical workflow for a 60-second video
- Edit the picture first. Sound effects after picture lock, never before. Re-cutting after sound design is wasted work.
- Watch the cut once with no audio at all. Mark every visible action that should make a sound. Most videos have 4 to 8.
- Generate or pull effects for each mark.
- Place, sync, duck.
- Listen on phone speakers. Then headphones. Then a laptop. If it works on all three, ship it.
If you're using an agentic system like Poolday, steps 2 through 4 happen automatically. You go from picture lock straight to the listen-back in step 5, and intervene only where the system's choices need adjusting. The same pattern applies to reframing across aspect ratios and localizing into multiple languages, which we cover separately.
What good sound design feels like
The viewer doesn't notice it. They notice the video feels expensive. They notice the cuts land. They notice they trust the brand a little more than they did 60 seconds ago.
Sound is the cheapest production upgrade in video. AI generation pulls the cost down further. Agentic editing pulls the manual labor out of placement. The remaining work is taste, and taste still belongs to you.
FAQ
Can AI generate any sound effect from a text prompt? Most foley-style organic sounds (footsteps, doors, fabric, weather, kitchen sounds) generate convincingly. Mechanical, synthetic, and highly specific sounds (a particular engine, a branded UI sound) often need multiple variations or a real recording. Prompt specificity matters: describe material, motion, environment, and what you don't want.
What's the difference between AI sound generation and an agentic video editor? A sound generation tool produces audio from a prompt. An agentic video editor watches the video, identifies which moments need sound, picks or generates the right effect, and times it to the visible action automatically. The first is a tool. The second is a workflow.
How loud should sound effects be relative to dialogue? Aim for 6 to 12 dB below the loudest dialogue peak. Effects should be felt, not consciously noticed. Always duck background music 6 to 8 dB under the effect for the duration of the hit.
When should I add sound effects in my edit? After picture lock, never before. Re-cutting after sound design forces you to redo the placement work.
How many sound effects does a typical 60-second video need? Most well-edited 60-second videos have 4 to 8 sound effects. More than that and the mix gets crowded. Fewer and the video feels under-designed.
Does AI-generated sound replace a real sound designer? For the mechanical work (sourcing, sync, basic mixing), yes. For taste-driven decisions on a high-budget piece (which actions to score, what emotional register, when silence is louder), human judgment still wins. Most creators don't have a sound designer at all, and AI tools take them from zero to professional-baseline in minutes.
Can I use AI-generated sound effects commercially? Most modern AI sound effect tools grant commercial use rights on generated output. Check the specific tool's license. Agentic editing systems that route to multiple sound providers typically clear this in the platform terms.
Want sound design that lands without the manual labor? See how the agent handles sound across real customer projects.