When you are able to conduct confidential conversations and are not able to overhear the conversations of others. There are different degrees of acoustic privacy, ranging from none to complete.

The measure of the intelligibility of speech. The Index is rated from 0.00 (no intelligibility) to 1.00 (perfect intelligibility). The range is divided into four qualitative privacy categories, including Confidential (0.00 to 0.05), Normal (0.05 to 0.20), Marginal (0.20 to 0.30), and None (0.30 to 1.00).

The standard measure of the sound pressure level that approximates the sensitivity of the human ear at moderate sound levels. A-Weighted Sound Level de-emphasizes high and low frequencies because the ear poorly perceives these.

Background noise is the noise present in an environment, other than the desired or foreground sound. Also referred to as ambient noise, it is the combination of all sounds generated both near and far.

Centralized systems consist of a centrally-located rack of electronic equipment used for masking generation, volume and equalization adjustments, and amplification. This equipment is connected to a set of loudspeakers installed above the ceiling that reproduce the centrally-generated masking sound.

Decentralized systems consist of Master and Satellite Units. The Master includes the electronics for sound generation, and controls for volume and contour adjustment. Local changes must be made by entering the ceiling and physically accessing those controls. Only global volume changes and timer functions can be centrally controlled. Also referred to as distributed or self-contained systems.

The unit of measure for sound pressure level (volume).

The variation in sound levels over time, or the difference between the loudest and quietest sounds measured over a period of time.

An audio system component that allows for the adjustment of the volume of specific frequency bands. Typical equalizers allow adjustment for each octave or one-third octave.

The equivalent constant sound level for a varying sound level measured over a period of time. Also referred to as the Equivalent Average Sound Level.

The number of cycles of sound waves per second.

The unit of measure for frequency.

The degree to which a conversation can be understood or is comprehensible.

A person’s subjective perception of the volume of sound. A 10dB increase in sound energy is generally perceived as a doubling in loudness.

The effect of reducing or eliminating the ability to hear a sound due to the presence of a masking sound.

The LogiSon Sound Masking System provides a complete system – random masking sound generator, amplifier, and separate volume and equalizer controls for masking and paging – in each Primary Hub. A small wall-mounted control panel provides central control of each of these features, as well as paging and timer functions. The hubs and speakers are typically installed above the ceiling.

Any unwanted sound. Note that not all sound is considered noise.

The lowest sound pressure levels present in a space over a period of time.

The measure of acoustical absorption calculated at specific mid-range frequencies. The Noise Reduction Coefficient is commonly used to rate the performance of acoustical ceilings.

Bands of frequency into which audible sound is divided for frequency analysis. One-third octave bands further divide each octave into three segments.

Occurs when identical sound waves from two speakers meet in the area between the two speakers. Constructive or destructive interference occurs, causing uncontrollable variations in the sound volume and frequencies.

A broad-spectrum sound exhibiting equal sound energy per octave. Each octave contains double the frequency range of the one before. In order to maintain equal energy, the volume must reduce at 3dB per octave.

The absence of noise. Quiet can be distinctly different from “silence.” Silence is the absence of all sound, while quiet is the absence of noise (i.e. unwanted sound).

A sound signal with no repetitive pattern.

The persistence of a sound in a space due to many reflections of that sound from the surfaces in the space after the sound source has been stopped. Reverberation can be compared to a multitude of indistinguishable echoes.

A quantitative and qualitative assessment of noise. The numeric component is the average of the sound pressure levels at the 500, 1000 and 2000 Hz octave bands, while the qualitative component classifies the noise as containing Rumble (R), Hiss (H), Vibration (V), or as being Neutral (N). The Room Criteria curves approximate the balanced spectrum found acceptable by most people.

The absence of any sounds. Silence differs from “quiet,” which is the absence of unwanted sounds. A space can be considered quiet even if an unobtrusive background sound is present.

The measure of the sound pressure level using weightings that emphasize certain frequencies. Weightings include designations such as A, B and C.

A device used to measure sound pressure levels. Meters consist of a microphone, amplifier, output meter, and frequency-weighting protocols.

See the definition for Masking.

The measure of the amplitude or volume of sound. Sound Pressure Level is measured in decibels (dB).

A classification of the sound-insulating properties of a material or structure. Sound Transmission Class is commonly used to rate office walls and furniture partitions.

The composition of a sound expressed in frequency and amplitude.

The measure of the sound-insulating properties of a material or structure, expressed as the number of decibels by which a sound is reduced in passing from one barrier (e.g. a wall or furniture) to another.