What is the maximum distance from the finished ceiling for wall-mounted audible notification appliances?

The maximum distance from the finished ceiling for wall-mounted audible notification appliances is set at 6 inches to ensure the effectiveness of the alarm's sound distribution. This distance is guided by the National Fire Alarm and Signaling Code, which seeks to optimize the audible alarms' performance in a given space. When the appliances are mounted closer to the ceiling than the specified distance, the sound output may be significantly affected due to sound reflection and absorption by the ceiling itself, thereby diminishing the overall effectiveness of the notification device. By keeping the distance at 6 inches, it allows for an unobstructed path for sound waves to travel, enhancing audibility and ensuring that occupants can hear the alarms promptly in case of an emergency.