CDDA to SPH Converter
Convert CD audio to NIST SPH speech format online
Research Standard
Produce NIST Sphere files from CDDA — the format required by major speech research corpora like TIMIT and Switchboard.
Server-Based
SPH conversion runs on our servers. No NIST tools or Kaldi installation required — convert CDDA to SPH from any browser.
Secure Handling
Your CDDA uploads are deleted after conversion. SPH outputs are removed from our servers within 24 hours automatically.
How to convert CDDA 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
Frequently Asked Questions
SPH (NIST Sphere) is the standard format for distributing speech research corpora. Converting CDDA to SPH makes recordings usable in academia.
Sphere is a format defined by NIST for exchanging speech data in research. It includes a text header with metadata and PCM audio data.
The NIST SPH tools, SoX, Kaldi, and HTK can read Sphere format. Most speech recognition research frameworks support it.
SPH can store audio at various rates. Speech research typically uses 8-16 kHz, but the format handles 44.1 kHz CDDA data as well.
Upload multiple CDDA files and convert to SPH in one session — practical for building speech research datasets from CD recordings.