Reels ads play with sound on: three ways to add audio to a silent clip

Meta's Reels ads page says Reels default to sound on, and the ads play with sound unless the viewer has turned it off. So a silent clip loses a channel. In Sume you can add audio three ways: pick a model with native audio, lay a soundtrack in a Timeline, or build the Timeline around a voice track.

What Meta's page says

"Instagram & Facebook Reels: Create Short Video Ads" (read 2026-10-05) says: "Reels default to Sound On. The ads will play with sound on if the user hasn't turned off the sound setting." It recommends 9:16 and key messages inside the safe zone.

Three ways in Sume

Pick by what you already have.

Mixing

Timeline 1.0 lets a soundtrack sit under a voice with duck_db from 0 to 20, which needs a real voice spine; audio.gain_db runs from -60 to 12. A silent spine is possible with audio.mode set to silence, but that is the case you are trying to avoid for Reels.

Fade the end with fade_out_seconds so the track does not stop mid-note.

{
  "audio": { "url": "https://media.sume.com/artifacts/artf_demo/vo.wav", "duration_seconds": 15 },
  "soundtrack": { "url": "https://media.sume.com/artifacts/artf_demo/bed.mp3", "gain_db": -12, "duck_db": 10, "fade_out_seconds": 2 },
  "video": [{ "source_url": "https://media.sume.com/artifacts/artf_demo/clip.mp4", "start": 0, "duration": 15 }]
}

Check

Play the result with the sound on. Meta's page also says audio and key messages in the safe zone matter, so confirm the voice is clear before you check anything else.

• Keep the voice louder than the bed.
• Do not rely on captions alone.
• Check a frame of the end card.