Is the buzzer a constant frequency? Does this frequency have to be detected in a quiet or noisy environment? What is the distance from the buzzer to the loudspeaker? What type of loudspeaker are you proposing to use? Regards Kev -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads