The Speech Module gives ACT-R a rudimentary ability to speak. This system is not designed to provide a sophisticated simulation of human speech production, but to allow ACT-R to speak words and short phrases for simulating verbal responses in experiments.
There is only one command to which the Speech Module responds, which is speak. speak takes one parameter, the string to be spoken. Like the Motor Module, this then starts a process of feature generation and finally execution.
Speech is output in up to two ways: actual synthesized speech (generated by the Macintosh Speech Manager) and/or a call to a user-supplied function at the time of speech onset. In order for synthesized speech to be produced, Apple's Speech Manager software (MacInTalk) must be installed on the machine on which ACT-R/PM is running. This software can be found on Apple's FTP server. Basic speech synthesis does not produce particularly good speech, but it's something.
A (probably more useful) output channel is a call to a user-defined Lisp function. This should be a function that takes two arguments: time and text. When the function is called by RPM, it will provide the simulated time (as a floating-point number, in seconds) at which speech began and a string containing the text that is being spoken. The user-defined function should be set via the :speech-hook-fct parameter.