Speech codecs differ from Audio codecs in that they are optimized for speech signals. Human speech can be modeled easier than generic audio. This means that high quality speech can be coded with specific methods better than generic audio. On the other hand humans are very good at hearing problems with human speech signal. This means that otherwise good quality generic audio codecs perform poorly with speech signal even at quite high bit rates.
The following 61 pages are in this category, out of 61 total. This list may not reflect recent changes (learn more).