AMB to SPH Converter

Convert Ambisonic B-Format audio to SPH online

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Spatial to Standard

Convert AMB Ambisonic recordings to SPH — make spatial audio accessible in a format suited for speech recognition research.

No Spatial Tools

Skip the ambisonic plugin setup. Convert AMB to SPH directly in your browser without specialized spatial audio software.

Fast Processing

AMB to SPH conversion runs on our cloud servers. Your Ambisonic recordings are processed and ready for download quickly.

How to convert AMB to SPH

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

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

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

About formats

AMB files contain audio encoded in Ambisonic B-format, a full-sphere surround sound technique conceived by Michael Gerzon during the 1970s. Unlike channel-based systems such as 5.1 or 7.1, Ambisonics captures a complete three-dimensional sound field using spherical harmonics — first-order B-format consists of four channels: W (omnidirectional), X (front-back), Y (left-right), and Z (up-down). This representation is speaker-independent, meaning one recording can be decoded to any loudspeaker arrangement or binaural headphones without remixing. AMB files typically store uncompressed PCM data and are processed by tools like SoX or specialized plugins. A core advantage is spatial flexibility — creators produce one master file that adapts to stereo, surround, or immersive playback. The format also scales elegantly: higher-order Ambisonics adds channels for increased spatial precision upon the same mathematical framework. With the growth of virtual reality, 360-degree video, and spatial audio for gaming, Ambisonics has experienced a resurgence, adopted by platforms like YouTube for immersive media delivery.

Developer: Michael Gerzon / Ambisonic Community

Initial release: 1975

SPH is the file extension for audio stored in the NIST SPHERE (SPeech HEader REsources) format, a standard created by the U.S. National Institute of Standards and Technology around 1990. Built for speech research, SPH files carry a 1024-byte ASCII header packed with metadata — database identifiers, channel counts, sample rates, byte ordering, and compression type — making every recording self-describing. The underlying audio is typically 16-bit linear PCM sampled at 16 kHz, though other configurations are permitted. Researchers at NIST, DARPA, and universities worldwide rely on SPH for distributing speech corpora such as TIMIT, Switchboard, and the LDC collections that underpin modern automatic speech recognition systems. A key advantage is that the human-readable header lets scripts parse recording metadata without binary decoding. The format's strict standardization also eliminates ambiguity when sharing datasets across institutions and platforms. Because SPH files store uncompressed PCM, they preserve full audio fidelity — critical when training acoustic models where even small artifacts can skew results.

Developer: National Institute of Standards and Technology

Initial release: 1990

Frequently Asked Questions

Why convert AMB to SPH?

SPH provides speech research corpus format. Converting AMB brings your spatial recordings into a format usable for speech recognition research.

What opens SPH files?

NIST tools, Kaldi, HTK, SoX can open SPH files for playback and editing without special plugins.

Does the spatial effect carry over?

AMB contains Ambisonic B-Format spatial data. Converting to SPH renders the audio to standard channels — the 3D spatial encoding is flattened.

What is AMB format?

AMB stores Ambisonic B-Format audio for VR, 360-degree video, and immersive spatial sound production. It is a specialized surround format.

Can I batch convert AMB files?

Upload several AMB recordings and convert them all to SPH at once — process your spatial audio collection efficiently.

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