Cheap mcu does not have enough MIPS to perform speech recognition. You must need DSP to do real time speech recognition. Microchip dspic is a good choice which is not too expensive and it has some libraries for you.
http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=1406&dDocName=en023596
No, Microchip dspic is mcu with dsp capability. It is general purpose mcu, not specific for Bluetooth application. If you need speech recognition on Bluetooth headset, the best approach is still work on BC5-MM but this will need more software work on SDK.
http://www.csr.com/products/16/bluecore5-multimedia