This article lists the outdoor warning sirens built by Biersach & Niedermeyer Co., Alerting Communicators of America and American Signal Corporation. Biersach & Niedermeyer Co. Alerting Communicators of America sirens American Signal Corporation sirens See also List of civil defense sirens References External links American Signal website Alerting Communicators of America website (defunct) The Siren Board - Alerting Communicators of America category The Siren Board - American Signal Corporation category Air Raid Sirens - 1992-1993 ACA-ASC Flyers Sirens