AVR to SPH Converter

Transform Audio Visual Research AVR into NIST SPHERE

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Research Audio Rescue

Extract audio from the legacy AVR format and convert to SPH — make Atari ST research recordings accessible in a supported format.

No Emulator Required

Convert AVR files without an Atari ST emulator or SoX command line. The entire process runs in your web browser.

Secure Processing

Uploaded AVR files are deleted immediately after conversion. Output files are purged within 24 hours.

How to convert AVR to SPH

1

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

2

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

3

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

About formats

AVR (Audio Visual Research) is an audio format that originated on the Apple Macintosh around 1989, created by the Audio Visual Research company for their editing and synthesis tools. It stores raw audio samples preceded by a fixed-length header containing sample rate, bit depth (8 or 16 bits), channel configuration, and loop point markers. Unlike complex container formats, AVR uses a flat binary structure with no compression, preserving the full waveform quality at the expense of larger files. The format served professional Macintosh audio workstations during the late 1980s and early 1990s, when the Mac platform dominated creative computing. One advantage is uncompressed storage guaranteeing zero artifacts and perfect signal integrity through editing operations. Native loop markers represent another feature, letting sound designers define seamless repetition points within the file — ahead of its time for sample-based music production. Tools like SoX maintain AVR support, ensuring archivists can access and convert these legacy recordings. While eclipsed by WAV and AIFF, AVR remains a notable piece of early digital audio history.
Initial release: 1989
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.
Initial release: 1990

Frequently Asked Questions

Why convert AVR to SPH?

SPHERE is the NIST speech corpus standard. Converting AVR speech data to SPH creates research-format audio.

What can open SPH files?

NIST SPHERE tools, SoX, HTK, and Kaldi read SPH.

What is the AVR format?

AVR (Audio Visual Research) is an audio format developed for the Atari ST computer. It was used in academic and research audio applications.

Is AVR widely supported today?

AVR is a niche legacy format. SoX and Audacity can read it on modern systems, but mainstream media players do not support it.

Can I convert multiple AVR files at once?

Yes. Upload several AVR recordings and batch-convert them all simultaneously — efficient for processing research audio libraries.