Sound masking in depth – achieving acoustic comfort and speech privacy


Sound masking is the addition of natural or artificial sound (sometimes less-accurately known as ‘white noise’ or ‘pink noise’) into an environment to ‘mask’ or cover up unwanted sound by using auditory masking.

Sound masking

The use of sound masking techniques can help to reduce or eliminate awareness of pre-existing sounds in a given area, to bring benefits such as acoustic comfort and speech privacy to the workspace.

Sound masking can be explained by analogy with light. Imagine a dark room where someone is turning a torch on and off. The light is very obvious and distracting. Now imagine that the room lights are turned on. The torch is still being turned on and off, but is no longer as noticeable because it has been ‘masked’. Sound masking is a similar process of covering a distracting sound with a more soothing or less intrusive sound.

Quell® sound masking systems, developed by Apple Sound, achieve this effect electronically by generating a pure, smooth and gentle signal and distributing it throughout the space by means of stable, high quality amplifiers and specially selected, precisely positioned loudspeakers. The loudspeakers can be mounted above a false ceiling, fitted directly into the ceiling grid or surface mounted in some cases.

Why use sound masking?

Results from studies point to noise in the workplace environment as a major cause of reduced effectiveness, higher stress and declining job satisfaction.

The modern, often open-plan office environment is particularly vulnerable to factors which contribute to the level of unwanted noise in the workspace, namely:

  • Increased workstation densities and decreased workstation sizes for all types of workers, which mean more employees are working in closer proximity to each other than ever before, reducing speech privacy.
  • Creation of office ‘teaming’ areas that increase noise levels as a result of the interactive conversations required in this type of environment.
  • More widespread use of speakerphones and the tendency of employees to speak more loudly when using them.

An effective sound masking system can help reduce these sources of stress and distraction and bring benefits such as improved concentration and productivity the workspace.

In addition, speech privacy is quickly becoming a concern in a variety of environments ranging from healthcare facilities, where doctor-patient confidentiality is critical, to banks, building societies and post offices where speech privacy is vital in preserving confidentiality and combatting fraud.

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Where can sound masking be used?

Sound conditioning can be used in any environment where there is a need for increased acoustical comfort and/or speech privacy and the background sound level is low. Sound masking is typically used in selected workspaces and public areas. The most common sound masking installations are:

Open Plan Offices

Open offices can be too quiet, making the conversations of others in the office distracting. Open offices can benefit from sound masking because the added sound covers existing sounds in the area – making workers less distracted, more productive and improving speech privacy.

Public Spaces

Sound masking as a speech privacy system is useful for reception areas, pharmacies, waiting rooms and financial institutions. The system is provided in the area where conversations should not be heard – not necessarily in the area where the conversation is taking place. For instance, a solicitor does not want those in the waiting room to overhear private conversations with a client so sound masking is provided in the waiting area to provide clients with speech privacy.

Private Offices

Private offices and other enclosed spaces often appear to provide speech privacy but actually do not. Walls are often lightweight and do not extend to the ceiling deck – only to the ceiling tile. In these cases, sound can easily travel through partitions or over the walls. Sound conditioning can be provided in adjacent private offices, or in hallways outside of private offices, to ensure that confidential conversations remain confidential.

What does sound masking sound like?

Nothing: correctly installed, the resulting ambient noise is not normally detectable by occupants. When heard in a silent environment, the sound can be compared to a gentle sound like air flowing through a vent.

How can Apple Sound implement a sound masking system for me?

Apple Sound is the developer and sole provider of the full range of Quell® products and services and as such offers site surveys, acoustic advice and technical expertise to our customer base.

As a fully-scaleable solution, Quell® sound masking systems can be implemented in a wide range of environments, from a village post office counter to a multi-floor open-plan office building.

Quell® systems are unique in using the -ism®2 sound masking signal generator, which produces a genuinely RANDOM signal (that cannot be ’cleaned’ from a recording – unlike pseudo-random digital noise sources used in other masking products).

The Quell® sound masking module forms a primary part of the core system along with a control input allowing the masking level to be controlled and a master level control. Stable, high-quality amplification and specially selected loudspeaker systems are optimised for each installation.

Apple Sound provide a complete specification, supply, delivery and installation service with long-term after sales support.

For an in-depth look at the current Quell® product range, please visit the dedicated Quell® page.