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 STL2023, incorporates: An implementation of P.50 fullband MNRU as described in ITU-T P.810. A tool for automatic instrumentation of speech and audio codecs to measure their computational complexity and memory. Recommendation ITU-T G.191 includes an electronic attachment containing STL2023 and manual.