Sound Tools Extended (STx) is an acoustic speech and signal processing application for Windows. It provides tools to analyse, visualise, segment, and annotate wave files. It uses it's own annotation file format, but can import and export PRAAT TextGrid files. The software is actively being developed at the Acoustics Research Institute in Vienna, and is used in a variety of acoustic fields around the world. For non-commercial, scientific and educational purposes, we offer STx free for download.

The upcoming version STx 5.0 will include a compact mode specially designed for linguists.

A list of changes per version of STx is available in the documentation wiki.


The documentation for STx 3.8 is available in the following formats: 



You can download STx 3.8 here.

The documentation for STx 3.7 is available in the following formats: 

You can download STx 3.7 here