If you want to do voice recognition for free, julius is the way to go.

https://qiita.com/t_oginogin/items/f0ba9d2eb622c05558f4

How to Install

No more weird errors.

http://soramame-tomotomo.blogspot.jp/2013/09/juliusios.html

julius recognition too slow

even after using this

https://qiita.com/t_oginogin/items/0634000e6713f9174b5f

So I gave up on julius.

If you pick up more than a certain volume, throw it to DOCOMO.

http://iroha112233.hatenablog.com/entry/2016/03/24/231620