Acoustics_vocabulary

 **﻿ **
 * ACOUSTICS VOCABULARY **

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

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.
 * Ceiling Attenuation Class (CAC) **

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

Unwanted sound. Noise can often be the individual perception of a particular sound, e.g. a background noise.
 * Noise **

A construction material consisting of a rigid panel of several layers of fibreboard or paper bonded to a gypsum core
 * Plasterboard **

The repetition of a sound resulting from reflection of the sound waves
 * Reverberation **

The sound level that is constantly generated in the room will, on the other hand, be effectively dealt with by the ceiling and be less dependent on sound-dispersing (scattering) objects. A sound absorption class A product provides the most effective decrease of the sound level.
 * <span style="color: #27a8dd; font-family: Tahoma,Geneva,sans-serif; font-size: 120%;">Sound level **

<span style="color: #800000; font-family: 'Trebuchet MS',Helvetica,sans-serif;">Suspended ceilings have a positive effect on speech clarity by reducing the reverberance in the room. A good, effective, sound-absorbing ceiling contributes to a good relation between early and late sound reflections in such a way as to benefit speech clarity.
 * <span style="color: #27a8dd; font-family: Tahoma,Geneva,sans-serif; font-size: 120%;">Speech clarity **

<span style="color: #800000; font-family: 'Trebuchet MS',Helvetica,sans-serif;">Similar to the RASTI method but a more complete form of measuring speech intelligibility by measuring all octave bands in the frequency range 125-8000 Hz.
 * <span style="color: #27a8dd; font-family: Tahoma,Geneva,sans-serif; font-size: 120%;">Speech Transmission Index (STI) **

<span style="color: #800000; font-family: 'Trebuchet MS',Helvetica,sans-serif;">RASTI is an objective way of measuring speech intelligibility. It is measured at two frequencies, 500 and 2000 Hz, by placing a loudspeaker, which transmits sound from the location of the person speaking, and a microphone where the listeners are situated. (See also STI).
 * <span style="color: #27a8dd; font-family: Tahoma,Geneva,sans-serif; font-size: 120%;">Rapid Speech Transmission Index (RASTI) **

<span style="color: #800000; font-family: 'Trebuchet MS',Helvetica,sans-serif;">The ability of a building element or building structure to reduce the sound transmission through it. The sound insulation is measured at different frequencies, normally 100-3150 Hz. Airborne sound insulation is expressed by a single value, Dn,c,w, Rw or R'w. Impact sound insulation is expressed by a single value Ln,w or L' n,w.
 * <span style="color: #27a8dd; font-family: Tahoma,Geneva,sans-serif; font-size: 120%;">Sound insulation **