How to Split Multiple Stereo WAV Files into Mono

What does "stereo to mono" mean?

The phrase is used for two different operations, and they give very different results.

A downmix makes sense when a stereo sound has to play back from a single speaker. Channel extraction is what you want when each channel carries its own source and you need to work on them separately. For a longer look at the difference, see splitting stereo to mono.

When should you split stereo files into mono?

Splitting is useful when the two channels are really two separate recordings stored in one file:

• a recorder set to write two independent microphones as a stereo pair,
• a boom on Left and a lavalier on Right,
• two wireless microphones, one per channel, for a two-person interview,
• field recordings where each channel needs its own edit, level or clean-up,
• preparing recordings for sound post-production, where each microphone gets its own track,
• delivering isolated channels to an editor or a re-recording mixer,
• separating channels before organizing, naming or archiving production audio.

Not every stereo file should be split. A stereo ambience, a spaced pair on an orchestra or a music mix depends on the relationship between Left and Right; that relationship is the stereo image. Split those files only if you really need each side on its own, and keep the stereo originals either way.

How to split multiple stereo WAV files into mono

The steps below follow Batch Stereo to Mono as it works today.

1. 1. Open Batch Stereo to Mono

   Open Batch Stereo to Mono. It is a separate tool from the single-file converter, built for running the same split on a whole folder of recordings.

2. 2. Add your stereo WAV files

   Drop several WAV files at once, or add more later. The tool reads the channel count from each file itself. Stereo files are split; mono files and files with more than two channels are marked as failed with a message explaining why, and the rest of the queue carries on. A damaged file is handled the same way.

3. 3. Choose your filename suffixes

   By default the Left file gets _L and the Right file gets _R, added to the original base filename. Both suffixes are editable and used exactly as you type them, so you can label the channels the way your project does. The tool does not know what is on each channel: a name like _Boom is your choice, based on how the recording was made. The queue shows both output names before you start.

   Suffixes	Interview.wav becomes
   _L / _R (default)	Interview_L.wav · Interview_R.wav
   _LEFT / _RIGHT	Interview_LEFT.wav · Interview_RIGHT.wav
   _Boom / _Lav	Interview_Boom.wav · Interview_Lav.wav

4. 4. Choose an output folder when supported

   In browsers that support it (Chrome and Edge on desktop today), you can choose an output folder and each mono file is written there as soon as it is ready. Existing files are never overwritten: a name that is already taken gets a number added. In other browsers, the files are saved as normal browser downloads, and the browser may ask once to allow multiple downloads.

5. 5. Process the batch

   Files are processed one after another. Each stereo source creates two mono WAV files, Left then Right, and both are saved as they become ready, before the next source starts. No ZIP is involved. Progress is shown per file, and failed or cancelled files can be retried when the batch has finished.

What happens to the audio?

The tool extracts the original Left and Right channels. The samples of each channel are copied into their own mono WAV file. It does not:

• sum Left and Right,
• resample the audio,
• change the bit depth,
• normalize the audio,
• apply gain,
• add any other processing.

For supported PCM and floating-point WAV sources, each mono output is a sample-for-sample copy of the corresponding source channel. The Left file holds only what was on the Left channel, and the Right file only what was on the Right channel.

Sample rate, bit depth and duration

The mono files keep the sample rate, bit depth and duration of the source.

96 kHz material stays at 96 kHz, and a 16-bit file stays 16-bit. If the mono files need a different sample rate afterwards, for example 48 kHz for a video edit, run them through the Batch Sample Rate Converter as a separate step.

What happens to BWF and iXML metadata?

Production WAV files carry information your editor and sound editor rely on: when the file was recorded, where it sits on the timecode line, and which scene and take it belongs to. See BWF metadata explained for the background.

Supported production metadata is retained or adapted for the new mono files. This includes:

• BWF recording information: description, originator and recording date,
• the timecode start, identical in the Left and Right files,
• relevant iXML project, scene and take information,
• markers, at the same positions, with supported marker labels,
• supported INFO tags.

Channel-specific information is adapted. A stereo file may describe two tracks; after extraction each mono file holds one channel, so its track information describes that one channel:

Track names come from the source file's own metadata; none are invented. A line is also added to the coding history saying which channel was extracted, after the recorder's own entries. Not every chunk written by every recorder or DAW is carried over; the supported metadata above is handled deliberately.

Stereo, dual mono and two independent channels

A two-channel WAV file is technically stereo, but it can hold two very different things: a true stereo recording, where Left and Right together form one image, or two unrelated mono signals that simply share a file.

If you are not sure what a file holds, listen to each side, or open it in the Audio Inspector to check its channels and metadata first. More on the recording side of this in mono vs stereo recording.

Batch vs splitting one file

Use Batch Stereo to Mono when many stereo WAV files need the same split. For a single file, the Stereo to Mono tool offers two export modes: Split into mono files, which gives separate Left and Right files like the batch tool, and Sum to one mono file, which is a downmix. If you use the single-file tool for extraction, choose the split mode.

The single-file tool is also the better choice when you want to listen to both channels before exporting, keep only one side, or export to another format. The batch tool always writes WAV at the source sample rate and bit depth. For files with more than two channels, such as polyphonic recorder files, use the PolyWAV Splitter instead; see what is a PolyWAV.

Working with large recording folders

• Files are queued and processed one at a time.
• Both mono outputs of a file are saved as soon as they are ready, then the next file starts.
• The whole batch is not held in memory at once, only the file being processed.
• If you stop the batch, the files already finished are saved.
• Keep the browser tab open until the queue has finished.

This makes long queues of production WAV files practical. It does not remove every limit: very long or high sample rate recordings still need a lot of memory, and older or low-memory devices may struggle with them. For very large jobs, split the folder into smaller batches.

Are the audio files uploaded?

Your audio files are processed locally in your browser. Each file is read, processed and written locally, one after another.