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Sound effects let you drop a sound or audio clip onto your video — a whoosh, a click, a sting, applause, or a bit of background music — layered on top of your voiceover. Your microphone audio keeps playing; the sound effect is mixed in alongside it.

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Where to find sound effects

  1. Open your video in the editor.
  2. Open Overlay in the sidebar.
  3. Find the Sound Effects section.

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Add a sound effect

  1. Move the playhead to where you want the sound to start.
  2. Click the plus button beside Sound Effects. This opens the Media Library.
  3. Pick a sound:
    • Browse Tella’s built-in sounds under Default. They’re grouped into Interface, Transitions, Reactions, Atmosphere, and Everyday.
    • Choose an audio file from your Personal or Workspace library.
    • Upload an audio file from your computer or generate one with AI.
  4. Click the play button to preview a sound. Click its tile to add it at the playhead.
Use the search box to filter built-in sounds by name or category. The picker is the same library you use for media/B-roll, filtered to audio. The sound effect is placed on the timeline at the playhead, with its waveform shown on the segment.
A selected time range wins over the playhead. If you have a range selected — on the timeline or in the transcript — the sound effect starts at the beginning of that range instead, and selecting several ranges adds one to each. Clear the selection first if you want the playhead to decide.A sound shorter than the range does not stretch to fill it: the card ends when the sound ends. A longer sound is trimmed to the range.
With the library open, you can paste a copied audio file (⌘V / Ctrl+V) to upload it straight into your Personal library.

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Drop audio onto the timeline

Drag one or more audio files from your computer and drop them where you want them to start on the playbar, or on the timeline shown in Cut, Zoom, Overlay, or Layout. Tella uploads each file, saves it to your Personal library, and adds it as a sound effect at the drop point. When the uploads finish, the editor opens the Overlay sidebar and selects the first new sound effect.
Drop a file on another clip’s section of the playbar to add it to that clip.

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Set when it plays

In the timeline:
  • Drag the start or end of the sound-effect card to change its duration.
  • Drag the card left or right to move it earlier or later.
  • Hold Option on Mac or Alt on Windows while dragging to turn snapping off.
The video preview follows the moving edge while you drag a duration handle, helping you line up the sound with the exact frame where it should start or stop.
You can add several sound effects and overlap them.

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Duplicate a sound effect

  1. Open the sound effect’s three-dots menu in the Overlay sidebar.
  2. Select Duplicate.
The copy keeps the same audio, source range, timing, and volume. It starts at the same point as the original, so move or retime it unless you want both copies to play together.

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Adjust the volume

Each sound effect has its own volume control. Select the sound effect in the Overlay sidebar, then drag the Volume slider in the control panel below it to set how loud it plays relative to your narration. The slider goes from 0 (silent) up to 200 %, so you can also boost a quiet sound above its original level. The default is 100 % (original volume).
Sound effects are mixed on top of your microphone audio — adding one never removes your voiceover. If a clip’s own sound is too loud, turn the sound effect’s volume down instead of re-recording.

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Edit or remove a sound effect

  • Select a sound effect in the Overlay sidebar to open its timing and volume controls.
  • Use its three-dots menu to remove it.

Related topics

Model Context Protocol (MCP)Add media overlaysAdd background music to your videoOverlays overviewAdjust audio levels