OGG to SPH Converter

Produce SPHERE speech research audio from OGG

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Speech Corpus Standard

SPH is the format behind major speech datasets — convert OGG recordings into properly formatted research audio.

Dataset Preparation

Process entire OGG speech collections to SPH simultaneously — prepare research corpora in one operation.

Online Conversion

No speech toolkit installation required — produce SPH files from OGG directly through your browser.

How to convert OGG 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

OGG Vorbis is an open, royalty-free lossy audio codec inside the Ogg container format, both developed by the Xiph.Org Foundation. Vorbis was designed as a patent-free alternative to MP3 and AAC, using modified discrete cosine transform (MDCT) coding with variable bitrate encoding that adapts to signal complexity per frame. Blind listening tests have consistently shown Vorbis delivering perceptual quality matching or exceeding MP3, especially in the 96-192 kbps range. The format supports sample rates from 8 kHz to 192 kHz and 1 to 255 channels, covering everything from mono voice to surround mixes. A standout advantage is the complete absence of licensing fees — game developers, streaming platforms, and hardware makers can implement Vorbis without royalty concerns. Spotify relied on Vorbis for years as its primary streaming codec for exactly this reason. The format also handles quality degradation at low bitrates more gracefully than many competitors, which is why it remains popular in video games where storage is tight and thousands of sound effects compete for space. VLC, Firefox, Chrome, and Android all provide native Vorbis decoding.
Initial release: May 1, 2000
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 OGG to SPH?

SPH (SPHERE) is the NIST-defined format for speech research datasets. ASR training pipelines and linguistic tools expect SPHERE-formatted input.

What uses SPH files?

Kaldi, HTK, NIST evaluation tools, and academic speech corpora like TIMIT and Switchboard use SPHERE as their audio format.

Is SPH the same as NIST?

SPH and NIST both refer to the SPHERE format — SPeech HEader Resources defined by the National Institute of Standards and Technology.

What sample rate does SPH use?

Speech corpora typically use 8 or 16 kHz. The converter handles resampling from the OGG source automatically.

Can I convert an entire dataset?

Upload a batch of OGG speech recordings and produce SPH output for every file at once — ready for ASR research.

OGG to SPH Quality Rating

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