SOU to VOX Converter

Browser-based SOU to VOX audio conversion tool

Drop files here. 1 GB maximum file size or Sign Up
to
Facebook Amazon Microsoft Tesla Nestle Walmart L'Oreal

Convert in Bulk

Got a collection of SOU recordings? Upload them in one batch and convert the entire set to VOX in a single session.

Format Upgrade

Moving from SOU to VOX transitions your audio from an obscure encoding to standard in IVR and telephony — a significant practical improvement.

Simple Workflow

Converting SOU to VOX takes just a few clicks. No software installation, no configuration headaches — just upload and convert.

How to convert SOU to VOX

1

Select files from Computer, Google Drive, Dropbox, URL or by dragging it on the page.

2

Choose vox or any other format you need as a result (more than 200 formats supported)

3

Let the file convert and you can download your vox file right afterwards

About formats

SOU is a raw audio format designation that functions as an alias for unsigned 8-bit PCM data (u8) in the SoX audio processing framework. Files with the .sou extension contain headerless, uncompressed audio samples stored as unsigned 8-bit integers — each byte represents a single amplitude value from 0 to 255, with 128 as the silence midpoint. Because there is no header, playback parameters such as sample rate and channel count must be specified externally. The default assumption is typically mono at 8000 Hz, though the data can represent any rate the recording hardware supported. The u8 encoding that SOU aliases is one of the simplest possible digital audio representations, predating structured audio containers like WAV and AIFF. Raw unsigned PCM was commonly produced by early sound cards and digitizers in the late 1980s and early 1990s, when storage constraints and limited processing power made headerless formats a practical choice. One advantage is absolute simplicity: SOU files can be read by any program capable of basic file I/O, with no parsing of container structures or metadata decoding required — useful for embedded systems, hardware diagnostics, and educational contexts where audio fundamentals are being explored. The format's minimal overhead also means that conversion to any modern container is lossless and instantaneous, since the raw PCM samples can be wrapped in a WAV or AIFF header without any transcoding.
Developer: SoX Contributors
Initial release: 1991
VOX is a headerless audio format built around Dialogic ADPCM encoding, widely adopted in telephony, interactive voice response (IVR) systems, and voice mail platforms since the 1980s. Each audio sample is compressed into 4 bits using an algorithm developed by Oki Electric and implemented in hardware on Dialogic Corporation's telephony interface cards. VOX files typically use a sampling rate of 6000 or 8000 Hz, producing extremely compact recordings optimized for speech intelligibility rather than musical fidelity. Because the format carries no header, playback software must know the sample rate and encoding parameters in advance — a trade-off that reduces overhead but demands careful file management. The primary advantage of VOX is storage efficiency: a one-minute voice recording at 8 kHz occupies roughly 240 KB, making it practical for systems storing thousands of prompts. Dialogic ADPCM conforms to the ITU-T G.726 standard, ensuring interoperability across telephony equipment from different vendors. Even as modern call centers migrate to IP-based systems with codecs like Opus, vast libraries of VOX recordings persist in legacy IVR deployments and compliance archives worldwide.
Initial release: 1983

Frequently Asked Questions

What makes VOX a better choice than SOU?

Since SOU has minimal 8-bit format unrecognized by mainstream audio software, switching to VOX provides Dialogic ADPCM compression.

What can I use to play VOX?

You can open VOX with SoX, Dialogic telephony systems, and IVR platforms.

Will I lose audio quality converting SOU to VOX?

SOU stores voice at very low quality. Moving to VOX makes the audio playable everywhere — quality stays consistent with the source.

Can I do this conversion from my phone?

Yes. The online converter is platform-independent — use it from any computer, tablet, or smartphone with a web browser.

Are there limits on SOU to VOX conversion?

Standard conversions work without restrictions for typical use. Premium plans provide additional speed and capacity for large workloads.

Is registration needed for this conversion?

No account is needed for standard conversions. Simply upload your SOU recording, choose VOX, and download the result.