Sensor relay switch on music -for attraction

[carguard]

hey , the appliction: its a theme park attraction, think haunted house!!
so someone walks in either a PIR or motion sensor or trip wire, switches on either a smoke machine or a amplifier playing music.
how can i do this ? rs232 or ir ?? and bearing in mind that it will need to repeat theis cycle as new people walk thru. so maybe just turning on power is not adasvnced enough.