Public Address (PA) systems in buildings like airports, railway stations, shopping centers, stadiums, or concert halls have to clearly inform persons in danger about escape information and directions in case of an emergency. People need to be given clear instructions so they can react quickly and in an orderly fashion - a Life Safety Code requirement.

Using a hand-held instrument, it is possible to commission the entire building by measuring just how intelligible the PA announcements will be when comprehensibility is most needed.