Sound applied to an environment to provide privacy in open areas. The term masking refers to the so-called cocktail-party effect where certain conversations are hard to pick out because similar sounds mask them. The ear-brain can be fooled into not hearing certain sounds if other sounds at lower volume but sufficient complexity are simultaneously present. Pink noise is most often used to cause intentional masking; its spectrum is shaped or filtered and fed to loudspeakers hidden above an acoustical tile ceiling.