Recommendation ITU-T G.191 provides source code for speech and audio processing modules for narrowband, wideband and super-wideband telephony applications. The set includes codecs, filters, noise generators. This edition introduces changes to Annex A, which describes the ITU-T Software Tools (STL) containing a high-quality, portable C code library for speech processing applications. This release of the STL, also known as STL2022, incorporates: An implementation of ESDRU (energy-based spatial distortion reference unit) as described in ITU-T P.811. An implementation of the loudness measurement algorithm as in ITU-R Rec. BS.1770-4. Recommendation ITU-T G.191 includes an electronic attachment containing STL2022 and manual.