Acoustics_Vocabulary

Absorption Class
Classification of sound absorbers into Sound Absorption Classes A-E, according to EN ISO 11654, including frequencies 200-5000 Hz.

Background noise (dB)
For example, speech, scraping chairs, humming ventilation, traffic, machinery and equipment, sound from corridors, adjoining rooms, playgrounds. Increased background noise can have long-term negative effects, such as illness, fatigue, decreased productivity and efficiency.

Ceiling Attenuation Class (CAC)
Single value for the laboratory sound attenuation of a suspended ceiling between two rooms according to ASTM E 1414. This measurement takes only into account the sound transmission through the suspended ceiling.

Flutter echo
Occurs when noise bounces between parallel surfaces in a room.

Noise Reduction Coefficient (NRC)
Single value for sound absorption according to ASTM C 423, derived as the mean value of 4 frequencies in the range 250-2000 Hz.

Privacy
Acoustic privacy between working places in open plan offices is expressed with the Articulation Class (AC).

Sound absorbers
Materials and structures with the ability to take up sound energy and convert it into other forms of energy. They improve room acoustics by removing sound reflections, thus reducing the noise and the reverberation time.

Sound absorption
Means that sound energy is converted into mechanical vibration energy and/or heat energy.

<span style="font-family: Verdana,Geneva,sans-serif;">Sound insulation
<span style="font-family: Verdana,Geneva,sans-serif;">The ability of a building element or building structure to reduce the sound transmission through it.

<span style="font-family: Verdana,Geneva,sans-serif;">Sound strength (dB)
<span style="font-family: Verdana,Geneva,sans-serif;">Measured in dB (deciBel). dB is measured at different frequencies. <span style="font-family: Verdana,Geneva,sans-serif;">dB(A) (or LpA) is a single-figure value used to describe the total sound strength for all frequencies in a way similar to the sensitivity of the ear. <span style="font-family: Verdana,Geneva,sans-serif;">dB(C) (or LpC) particularly focuses on low frequencies and better reflects how a sound is perceived by people with impaired hearing.

<span style="font-family: Verdana,Geneva,sans-serif;">Speech intelligibility
<span style="font-family: Verdana,Geneva,sans-serif;">Speech intelligibility is directly dependent on the level of background noise, reverberation time and the shape of the room.