Audio Merger
Layer several audio files into one mix. Put background music under a narration, combine instruments recorded separately, or add ambience to a voice track, with a volume control for each track and optional automatic ducking.
- Files stay on your device
- No sign-up
- Free to use
Mix
All tracks play at the same time. The first track in the list is the main track (for example a voice), the others play underneath it.
Output
Processing happens on your device; your audio is not uploaded.
How to use Audio Merger
- Drop two to six audio files. The first file in the list is the main track; drag files to reorder them.
- Set the volume of each track. Background music usually works at 20–40%.
- Choose whether shorter background tracks loop, and whether to duck them under the main track.
- Select Merge tracks and download the mix as MP3, M4A or WAV.
Audio Merger features
Simultaneous mixing
All tracks play together, mixed into a single file.
Per-track volume
From silent to double volume, set for each track independently.
Loop background music
Shorter music beds repeat until the main track ends.
Automatic ducking
Background tracks get quieter whenever the main track is speaking, like radio and podcasts.
Clipping protection
A limiter prevents distortion when loud tracks add up.
Runs locally
Nothing is uploaded.
When to use Audio Merger
- Adding background music to a voice-over, podcast intro or presentation narration.
- Combining separately recorded instruments or vocals into a demo.
- Adding ambient sound to a meditation or audiobook recording.
- Creating a soundtrack for a video before adding it in an editor.
- Mixing a sound effect under a spoken message.
Audio Merger FAQ
What is the difference between merging and joining?
Merging, as here, plays files at the same time and mixes them. Joining plays files one after another. Use the Audio Joiner to combine tracks in sequence.
How long is the result?
As long as the main (first) track. Background tracks are looped or cut to match it.
What does ducking do?
Ducking automatically lowers the background whenever the main track is loud, then lets it rise again in pauses. It keeps speech clear without manually adjusting the music.
What volume should background music have?
Usually 20–40% of its original level under speech. Use the result preview to check that every word is easy to understand.
Can different formats be mixed?
Yes. Files are converted to a common sample rate before mixing, so MP3, WAV, M4A and others can be combined.
Mixing audio: levels, looping and ducking
Mixing adds the waveforms of several tracks together sample by sample. Because the values add up, the combined signal can exceed the maximum level and distort, an effect called clipping. This merger keeps each track at the level you set and passes the mix through a limiter, which gently holds peaks below the maximum instead of letting them clip.
Balance is the most important part of a voice-and-music mix. Music that is too loud makes speech hard to follow, especially on phone speakers. A good rule is to set the music so it is clearly audible in pauses but sits well below the voice when someone speaks. Listening to the preview on the device your audience will use is the best test.
Ducking automates that balance. A sidechain compressor listens to the main track and reduces the background whenever the voice is present, restoring it during pauses. Radio presenters and podcast producers use this technique so music can be fuller between sentences without competing with speech.
Loops let a short music bed cover a long narration. For a smooth result, choose music designed to loop, which starts and ends at matching points; otherwise the repeat may be noticeable.