A research group is planning a good environment for recording a Portuguese Acoustic corpus, as most of them are still low quality.
What is a good quality omnidirectional microphone and unidirectional for that purpose?
Any suggestions for the environment and equipments are welcome.

The discussion of microphones on this forum  is specifically for people who are using the software VoxCommando. VoxCommando uses Microsoft's existing speech engine, so no one here has been involved in building new language corpora.

You might have more luck contacting someone involved in Carnegie Mellon's Sphinx project, such as Evandro Gouvêa (see http://egouvea.users.sourceforge.net/index.html). The Sphinx folks are always looking for help in building their corpus.