Alexey Guseynov's blog

Currently there are two free navigation applications for n900: mapero and navit. Both are using text to speech syntheses for voice navigation. This problem is solved more or less well for English language, but problem of Russian speech syntheses is much more complicated. It is supported in espeak and festival (launching festival on n900 is another story) but espeak speech quality is wery poor. You need too much attention to understand what it is saying, so it is not suitable for voice navigation. Festival with voice developed in MSU is good, but requires about 130 MB of RAM at moments of synthesis. n900 has 256 on board, so festival is very slow and it takes about 30 seconds to generate a phrase. Not suitable too.