Sound masking is an ambient background sound that is precisely tuned to target the same frequency as human speech, decreasing its intelligibility. Sound masking does not eliminate sound, but it does make distant discussions more difficult to follow and thus less likely to distract one, therefore increasing conversation privacy.
Simply put, conversations that would typically disturb someone working at a distance of more than 20 feet will be noticeably less intelligible or audible. Conversations at a distance fade into the background, and speech privacy is maintained, so face-to-face communication with coworkers is unaffected.
Sound masking off
Sound masking on
