Principles of Sound Masking

Principles of Sound Masking

By John Vellone

Sound Masking, Reducing noise in the work environment

Masking those sounds to decrease speech intelligibility with Sound Masking..

This improvement in speech privacy can be of great value in open-plan offices, doctors’ examination rooms, call centers and other environments where confidentiality is important.

Sound Masking

Sound masking can also reduce the distraction caused by traffic, office machinery and other unwanted sounds. Speech privacy is the primary focus of most sound masking systems.
A sound masking system emits low-level, non-distracting masking noise designed to reduce speech intelligibility and thereby improve speech privacy.

What is Sound masking
A sound system designed specifically to reduce or destroy speech intelligibility is called sound-masking.
Most speech sounds occur in the frequency range of 200 to 5000 Hz., therefore we use electronic spectral filters to generate random noise to favor those frequencies when masking noise is near or below the signal frequency.

Back Ground Music VS Sound Masking
Background music cannot function as a sound-masking system are: that all the frequencies in the spectrum are present to 20 KHz. and are of unequal amplitude, whereby sound-masking is specifically tailored for speech frequencies and of equal amplitude.
However, background music and sound-masking can compliment one another in that both can be working at the same time acoustically

How It Works
Research revealed that office workers in typical open office environments were only comfortable if the ambient background sound was in the very narrow range of 45 dB – 48 dB. At levels below this range, intruding speech became sufficiently distracting, affecting worker concentration. If levels exceeded 48 dB, the ambient sound itself was considered to be annoying or unpleasant to many of the workers.
In an open-plan office, the sound-masking level should be 4 to 8 decibels (A scale) louder than the intruding speech from adjacent workstations.

Consistent Sound
If you are considering using a sound masking system to improve speech privacy in your facility, your objective is most likely to either to protect confidential conversations or to reduce conversational distractions between workspaces. In either case, your goal is to reduce speech intelligibility while maintaining a comfortable work environment

Speaker Placement

How Many Speakers

Good Coverage
1 Speaker per 225 Sq. Ft.

Acceptable Economy
1 Speaker per 250 Sq. Ft
Tools for Sound Masking
(Hardware Tools….
Available Systems)

Mini-System I. Single self-contained masker. Single application.
Mini-System II. Any number of self-contained maskers. Special applications.
Small System. 1 or 2 channels (masking/paging), 1 or 2 zones. Up to 50,000 Sq. Ft.
Large System. Up to 8 channels (masking/paging), 30 zones, and 3600 speakers.
Varizone System. IP addressable masking/paging. Very large versatile system.

Hardware Tools: Mini-Maskers


Used for small areas or special applications.
Each masker has its own masking spectrum and level.

Structure of Larger Systems


Generators. They shape the masking and paging signal. They may contain mixers.
Amplifiers. They provide the power to drive the speakers.
Zone Controls. They create the level in zones and provide the owner with control.
Speakers. They create the sound field.

Sound-masking properly implemented can have a high degree of satisfaction and acceptability to persons subjected to them.

White Papers and Documents on Sound Masking

White Paper on OPEN PLAN ACOUSTICS -A PRIMER By Philip H .Nelson



Government Facilities and Commercial Corporate installations

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