Wickenhaeuser is providing an any 8051/ single pin solution:

http://212.227.69.250/ftp/projekte/Speech.zip

Maybe a newer (and english package) is now
available. The company is offering it's new C- compiler right here - just visit the online store ;o))

Some months ago a similar question came up in the Bascom group and has been nicely solved with the above mentioned package.

wolf