So you have five different machines? Each machine has a separate relay contact closure to indicate that it has a problem. You want a single central console with an audio amplifier and speaker which makes different announcements depending on which machine has a problem?
Why not use lights to indicate which machine has a problem? Could be a big light overhead each machine, or the lights can be located at the central console. A simple sonalert can be used to indicate that at least one machine has a problem, so as to cause the supervisor to look at the lights to see which machine(s) are alarming.