Lexicon Overview
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Hertz
Hertz (Hz) is the unit of frequency, where 1 Hz corresponds to one oscillation cycle per second.
Sound reduction index R
Sound reduction index R is a logarithmic value that quantifies the level of sound insulation provided by building components. R depends on the frequency and angle of incidence of the sound waves. The sound reduction index describes the sound insulation capacity of a given material. It is calculated as the ratio of the total incident sound intensity to the amount of sound intensity that the material lets through. A high R value equals a low transmission factor and hence a high sound insulation effectivity.
Sonic speed
Sonic speed (or: speed of sound) cs is the distance travelled per unit of time by a sound wave as it propagates through an elastic medium. The propagation speed depends heavily on the type, temperature and density of the medium. In dry air at 20°C (68°F) and 1 bar air pressure, the speed of sound is 343.2 m/s (1,126 ft/s).
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Sound insulation
Sound insulation is the acoustic shielding of a room or device in order to prevent or reduce the transmission of air-borne or solid-borne sound to neighboring spaces. The aim is to prevent the sound from propagating by using sound insulation materials to build a sound barrier around the noise source.
Threshold of pain
The threshold of pain (or: pain threshold) is the sound pressure level above which people perceive a sound event as being painful. For most people, the acoustic threshold of pain lies between 120 dB and 140 dB.
Closed-cell foams
In closed-cell foams, the walls between the individual cells are completely closed. As this prevents the penetration of liquids and vapor etc., closed-cell foams are suitable for use also in spaces with increased moisture load.