White-Noise Speakers

My company is investigating installing white-noise speakers to help drown out floating conversations around the office.  This intrigued me, so I did a little research on them.  Apparently, white is not the only color you can get.  Each color hits a different wavelength of noise, so you can target the high tones, low tones, etc.  One company even has a setup that if configured just right will also block conversations involving unpleasant tasks and assignments sent via e-mails and instant messenger.  They're called the "Selective Listener" speakers, but I'm pretty sure our office must already have those installed.