How to Mix Audio Files: Balance and Combine Two Tracks

To mix audio files, place them on separate tracks, set when each starts, adjust their levels and export the combined sound. For example, you can place a music bed under narration or add an effect beneath a voice. Listen to the overlap and the actual exported file before sharing it.

Mixing is different from joining: mixed clips can play at the same time, while joined clips play one after another. If you need a sequence rather than an overlap, use an audio joiner or follow the MP3 joining guide.

Before you mix: plan the timing

Keep the original files and use audio you have permission to combine. Decide which track should start first and which sound should remain clearest. For narration with a music bed, make a note of when the voice should begin and where the music ends. A separate backing track provides more control than music already mixed into the voice recording.

For example, if music starts at 0:00 and the voice begins at 0:04, the narration needs a four-second start offset. Listen to the start and ending: if the music ends before the speech, either prepare a longer bed or use an editor that can arrange multiple clips. A mixer does not automatically lengthen a file or create a fade.

Mix two short MP3 or WAV files in your browser

1. Open the files. In the Saturalabs audio mixer, choose two supported mono or stereo MP3 or WAV files. Each input must fit 50 MiB and five minutes; the output must also fit both limits. The files are decoded locally in a compatible browser.
2. Set the timing. Track 1 starts at the beginning. Choose when Track 2 begins using its start offset. To start music first and narration four seconds later, put music on Track 1, voice on Track 2 and set its offset to four seconds.
3. Set levels. Adjust each track's level. For voice over music, lower the music until words remain intelligible; there is no universal percentage that works for every recording.
4. Create and listen. Prepare a WAV or MP3 and preview the actual output. Check the lead-in, quiet words, loudest overlap and ending. Changing a setting clears the prepared export, so create a new preview after an adjustment.
5. Download and verify. Save the file and play it in the intended player or editor. Keep the original tracks for later changes.

The tool mixes two whole files; it does not trim, loop, add fades, detect beats, pan tracks or automatically duck music under speech. If summed decoded samples exceed full scale, it reduces the complete mix uniformly and displays the reduction. This protects decoded sample peaks, not true peaks; MP3 encoding may create higher reconstructed peaks.

Mix tracks in Audacity for more control

1. Import each source. Use File → Import → Audio to bring the files into separate tracks. Confirm each track contains the intended material.
2. Arrange the overlap. Position the clips on the timeline so they begin where needed. Play through the transition rather than assuming that matching clip starts is always correct.
3. Balance the tracks. Adjust each track's gain/volume control and listen to them together. If the playback meter shows clipping, reduce levels and check the loudest overlap again.
4. Export a copy. Choose File → Export Audio, select the desired range and format, and save. Audacity mixes the audible tracks during export; check mute and solo states first. Keep the editable project and source files.

Audacity's editing FAQ describes importing, balancing and exporting multiple tracks. Its mixing guide notes that explicit Mix and Render behaves differently from ordinary playback/export with muted tracks, so check the operation and selection you use.

How to choose WAV or MP3

Need	Starting choice	Check
Further editing or picture sync	PCM WAV, if accepted by the editor.	File size, sample rate and timing. A new WAV cannot recover detail already lost in the sources.
A smaller listening copy	MP3 at a suitable bitrate.	Listen for encoding changes and check timing; an MP3 encode can add delay or padding.

If a mono file is mixed with a stereo file in Saturalabs, the mono signal is placed equally in both output channels and the stereo source retains its channel positions. Listen in the intended playback environment; the tool does not offer individual pan controls.

Fix common mixing problems

• Music masks the voice: lower the music and compare a quiet spoken passage. A fixed level cannot follow every change in speech automatically.
• The mix sounds distorted: inspect each source separately, then reduce the levels feeding the mix. Distortion already recorded in a source remains.
• A cue starts late: check the second track's offset and the beginning of the exported file. For picture sync, compare a clear cue near the end too.
• You need an effect to fade: prepare that fade in a suitable editor before mixing, or use a multitrack editor that supports automation.

For more on live and software controls, see what an audio mixer does. A finished mix is not the same as the original independent tracks; keep them when later edits are likely.

Common questions

Can I mix a voice recording and music?

Yes. Use separate permitted files, start them at the intended times, lower the music as needed and check intelligibility throughout.

Is mixing the same as merging audio files?

“Merge” can mean either overlap or sequence. Mixing combines sounds that play simultaneously; joining end to end makes a longer sequence.

Can I change one source after exporting the mix?

Not independently with the same control as the original tracks. Keep the sources or project; separation from a finished mix produces an estimate and can alter the sound.