But is it really fissible with 8052
I thought this was "Speech recognition", not nuclear fission :-)

I am sure it is feasible with a '51, especially the very high speed derivatives from SILabs, some of which (F12x series) even have a MAC.
The question is NOT "is it feasible" the question is is "is this the best chip" which I doubt.
Today you can get e.g. ARM derivatives for about the same price as a '51 and, for speech you would be even better off using a low end DFSP.

So many projects have been proposed (e.g. multitasking) for the '51 where the issue is wrestling a processor into doing something it was never intended for.

The question really is "why do you want to do it with a '51?"

Erik