Dear Raul,

There must be a specific purpose why you want to do,what you asked.

To my knowledge ( I may be wrong ) this will call for a very fast clock rate and even then I am not sure if your voice sample rate can be anything near what you want it to be.

Assuming you cross this hurdle then comes the aspect of storage - the normal EEPROMS will be quite limiting even if you want to store voice collected over a few seconds. This will be a compromise between the final playback quality that you need and the time for which you want to store.

No somehow this is going to be quite a task for a 8051.

Would be nice to see some more views on this.

Raghu