Visual aid

摘要

The aim of the forthcoming BS EN 54-23: Fire detection and fire alarm systems. Visual alarm devices. is to ensure that any individual with a hearing impairment is notified in the case of a fire. An estimated nine million people in the UK are classed as deaf or hard of hearing. The term'hearing impairment'also refers to individuals whose hearing may be temporarily affected by external factors. Hearing can be impaired in areas of high ambient background noise from the use of ear defenders or even the intentional limiting of an audible alarm. In these situations, audible alarms are not considered to be effective alone as a means of warning device.