TTA to SPH Converter

Transform True Audio into NIST Sphere SPH online

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Corpus Standard

NIST Sphere is the established speech corpus format — lossless TTA gives researchers pristine audio data.

Research Ready

SPH integrates with Kaldi, HTK, and Praat — key tools for speech recognition and linguistic analysis.

Data Protection

TTA uploads and SPH outputs are handled securely — source deleted immediately, results within 24 hours.

How to convert TTA 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

TTA (True Audio) is a real-time lossless audio compression codec developed by Aleksander Djourik, with its origins tracing back to the early 2000s. The format reconstructs the original PCM stream bit-for-bit upon decoding, guaranteeing that no sonic detail is lost during storage or transfer. TTA handles standard CD-quality audio as well as high-resolution content up to 32-bit integer samples, making it suitable for everyday listening and professional archiving alike. Processing speed is one of TTA's defining strengths — the codec achieves fast encoding and decoding without heavy CPU demands, keeping it lightweight even on older hardware. The file structure supports ID3v1, ID3v2, and APEv2 metadata tags, so track information and album art travel with the audio. Hardware support appeared in several portable players, giving TTA a practical edge over some competing lossless formats. The open-source reference implementation ships under the GNU GPL, encouraging community adoption and third-party integrations. While newer codecs like FLAC have captured a larger share of the lossless audio landscape, TTA continues to serve users who value its simplicity and transparent compression.
Developer: Aleksander Djourik
Initial release: 2003
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

What is SPH?

SPH (NIST Sphere) is the audio format from NIST used for distributing speech corpora and linguistic research data.

Why convert TTA to SPH?

Speech research databases use NIST Sphere. Lossless TTA provides clean speech recordings for the corpus.

What reads SPH?

Praat, HTK, Kaldi, NIST tools, and speech recognition frameworks handle SPH for linguistic research.

Is quality preserved?

SPH supports uncompressed PCM — lossless TTA quality is fully preserved in the conversion.

Is my data secure?

TTA uploads are deleted immediately. SPH corpus files are removed within 24 hours.