Supplementary to Audible Alarms: VADs are especially powerful in high-sound regions or where Listening to safety is worn, supplementing conventional audible alarms. So as to avoid discrimination, BS EN 54-23 compliant VADs may be installed in all sanitary accommodation (not just WCs) and all hotel bedrooms, pupil accommodation and equivalent https://www.firesense.co.uk/type/addressable-fire-system/addressable-sounders-vids-vads/