ok, it looks like you are still learning how to control LEDs, there is a bit of learning curve before you get to signal processing or voice recognition.
Zilog has bunch of samples included with it's software (ZDS which is free from Zilog website). Also there are submissions that users have submitted as part of the z8 encore programming competitions.
here is one of code samples included with ZDS that uses serial port button(s) and LED(s). you can lower baud rate if you like.
note, this is from ZDSII 4.9 which is quite old now. just get current version from Zilog