Sound masking is a technique which is used to render unwanted sound inaudible, making people more comfortable. There are a number of uses for sound masking, ranging from making an open plan office more private and comfortable to work in to making it easier for people in noisy environments to sleep. Several methods can be employed to achieve sound masking, ranging from using systems which are integrated into a building to using standalone speakers for direct field sound masking.

This noise reduction technique is accomplished by playing a consistent, harmonious background sound which drowns out unwanted noise. For an example of how sound masking works, imagine standing in the kitchen with the water running and trying to listen to a conversation in the next room. The noise of the conversation is still present, but the sound of the water overwhelms it. The same principle holds true in sound masking systems.

Sounds of both natural and artificial origin can be used for sound masking. The sound is usually unobtrusive, and designed to be harmonious and pleasant. If people listen for it, they can hear it, but they rapidly become accustomed to the sound, with most people being unaware that a sound masking system is in use. Systems which project noise through speakers mounted in or from the ceiling are common in big structures, and it is also possible to install individual sound masking speakers or white noise machines to control noise pollution in smaller environments.

People use sound masking for a variety of things. Privacy is often an issue, with sound masking ensuring that the sounds of private conversations cannot be overheard. This technique may also be used to muffle sound in a loud environment so that people can concentrate and focus, or so that sounds do not create interference. Call centers, for example, utilize call masking so that phone conversations do not bleed into each other.

Typically, a sound masking system is adjustable. The nature of the sound can be changed, as can the volume level and the directionality of the speakers or sound masking devices. Companies which specialize in installing sound masking systems can set up the system and set basic levels, and provide information about adjusting it to meet specific needs. People can also install their own sound masking systems, and in a pinch, a crude technique like installing a fountain or playing a white noise recording on a stereo system can be used for effective sound masking.