Acoustics - What has changed during the past four decades:developments in building acoustics 1974-2014

This article traces developments in building acoustics through progress reported in Acoustics Bulletin over the past 40 years in technical papers, reports of the Building Acoustics Group, standardization and product innovation. The last 40 years have been exciting times in auditorium acoustics, in which major progress has been made. The auditorium acoustics world is international, relying on communication in journal papers and specialist meetings. The IOA has contributed in a major way with a very successful series of Auditorium Acoustics conferences, mostly linked to individual auditoria. Improved methods have been gradually developed, using beams rather than rays.