VOX to NIST Converter

Save Dialogic VOX recordings in NIST SPHERE format

Choose Files

Drop files here. 1 GB maximum file size or Sign Up

Telephony Research Data

NIST integrates telephony audio into academic speech research — real-world voice data in the standard corpus format.

Corpus Building

Convert VOX call recordings to NIST in bulk — efficient for assembling telephony speech datasets.

Data Security

Speech data requires confidentiality. VOX uploads deleted immediately, NIST outputs within 24 hours.

How to convert VOX to NIST

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

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

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

About formats

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.

Developer: Dialogic Corporation

Initial release: 1983

NIST SPHERE (SPeech HEader REsources) is a specialized audio file format created by the National Institute of Standards and Technology for speech research, particularly projects funded by DARPA. The format wraps raw audio samples with a structured ASCII header encoding metadata such as sample rate, channel count, encoding type, speaker demographics, and transcription annotations — making it ideal for distributing speech corpora. NIST files typically store uncompressed PCM or mu-law audio at telephone-quality sample rates (8 kHz or 16 kHz), though the container is flexible enough to hold various encodings. A key advantage is the rich self-documenting header that lets researchers embed detailed corpus metadata directly in the file, eliminating sidecar files. SPHERE has also become the de facto standard for major speech databases like TIMIT, Switchboard, and the Fisher corpus, ensuring broad recognition across academic and government labs. The open specification and availability of command-line tools (sphere, h_strip, w_decode) make it straightforward to convert, inspect, and process these files programmatically in speech processing pipelines.

Developer: National Institute of Standards and Technology

Initial release: 1990

Frequently Asked Questions

Why convert VOX to NIST?

NIST stores audio with rich metadata for speech research. Converting VOX integrates telephony data into academic research workflows.

What can open NIST files?

NIST SPHERE toolkit, SoX, Kaldi, and HTK all support NIST format.

How does NIST differ from SPH?

They are the same format. NIST is sometimes used as the extension or format name; SPH is the standard extension.

Is NIST used in Kaldi?

Yes — Kaldi reads NIST SPHERE files natively for speech recognition training and decoding.

Can I add metadata?

NIST supports rich text-based metadata headers for speaker info, recording conditions, and more.

Related Conversions

VOX to MP3

VOX to WAV

VOX to OGG

VOX to M4A

VOX to WMA

VOX to GSM

VOX to VOC

VOX to IMA

VOX to MP2

VOX to NIST

VOX to FLAC

VOX to PVF

VOX to CVS

VOX to AAC

VOX to AC3

VOX to AIFF

VOX to AMR

VOX to M4R

VOX to DTS

VOX to OPUS

VOX to SPX

VOX to CAF

VOX to W64

VOX to WV

VOX to TTA

VOX to RA

VOX to OGA

VOX to PRC

VOX to MAUD

VOX to 8SVX

VOX to AMB

VOX to AU

VOX to SND

VOX to SNDR

VOX to SNDT

VOX to AVR

VOX to CDDA

VOX to CVSD

VOX to CVU

VOX to DVMS

VOX to VMS

VOX to FAP

VOX to PAF

VOX to FSSD

VOX to SOU

VOX to GSRT

VOX to HCOM

VOX to HTK

VOX to IRCAM

VOX to SLN

VOX to SPH

VOX to SMP

VOX to TXW

VOX to WVE

VOX to SD2

Specific converters

MP3 to NIST

MP4 to NIST

WAV to NIST

FLAC to NIST

M4A to NIST

FLV to NIST

PVF to NIST

VOX to NIST

3GP to NIST

3G2 to NIST

AAF to NIST

ASF to NIST

AV1 to NIST

AVCHD to NIST

AVI to NIST

CAVS to NIST

DIVX to NIST

DV to NIST

F4V to NIST

HEVC to NIST

M2TS to NIST

M2V to NIST

M4V to NIST

MJPEG to NIST

MKV to NIST

MOD to NIST

MOV to NIST

MPEG to NIST

MPEG-2 to NIST

MPG to NIST

VOX to NIST Quality Rating

5.0 (1 votes)

You need to convert and download at least 1 file to provide feedback!