Acoustics_Vocabulary

Articulation Class (AC) A classification of suspended ceilings according to their ability to contribute to the acoustic privacy between work stations. AC is calculated from the Interzone Attenuation according to ASTM E-1110. The Articulation Class (AC) can be calculated from the interzone attenuation. This can then be used as a tool to classify and compare acoustic ceiling systems. The higher the AC the better the speech privacy in an open plan situation. We recommend that you use a suspended ceiling with minimum Articulation class 180 in order to achieve acceptable speech privacy. A high Articulation Class gives some privacy, a lower Articulation Class means lower privacy. Confidential conversation and work tasks demanding concentration need good privacy. 

 Articulation Loss of CONSonants (%-Alcons) One method of objectively measuring speech intelligibility is Articulation Loss of CONSonants (%-Alcons), showing the number of consonants being missed as a percentage. Consonants play a much more significant role in speech intelligibility than vowels. If the consonants are heard clearly, the speech can be understood more easily.
 * ** AC ** ||||||||||||||  ** Products ** ||
 *  200 ||||||||||||||  Master A/alpha   ||
 *  190 ||||||||||||||  Master C, Ds, E/alpha, Combison Duo A, E, Focus A, Gedina A.   ||
 *  180 ||||||||||||||  Focus C, Ds, Dg, E, Gedina E   ||
 *  170 ||||||||||||||  Master A/beta   ||
 * <span style="display: block; font-family: Arial,Verdana,Tahoma,Helvetica; font-size: 8pt;"> 130 |||||||||||||| <span style="display: block; font-family: Arial,Verdana,Tahoma,Helvetica; font-size: 8pt;"> Master A/gamma   ||

<span style="color: #666666; font-family: Arial,Verdana,Tahoma,Helvetica; font-size: 15pt;">Rapid Speech Transmission Index (RASTI) <span style="display: block; font-family: Arial,Verdana,Tahoma,Helvetica; font-size: 10pt;">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="display: block; font-family: Arial,Verdana,Tahoma,Helvetica; font-size: 10pt;"> <span style="color: #666666; font-family: Arial,Verdana,Tahoma,Helvetica; font-size: 15pt;">Sabine <span style="display: block; font-family: Arial,Verdana,Tahoma,Helvetica; font-size: 10pt;">The physicist Wallace Clement Sabine (1869-1919) created in Riverbank, west of Chicago, the well known Sabine formula (T=0,16V/A), showing the relationship between reverberation time (T s), room volume (V m³) and the amount of absorption (A m²). <span style="display: block; font-family: Arial,Verdana,Tahoma,Helvetica; font-size: 10pt;">(image): (Sabine's formula) <span style="display: block; font-family: Arial,Verdana,Tahoma,Helvetica; font-size: 10pt;"> <span style="display: block; font-family: Arial,Verdana,Tahoma,Helvetica; font-size: 10pt;"> <span style="color: #666666; font-family: Arial,Verdana,Tahoma,Helvetica; font-size: 15pt;">Speech intelligibility <span style="display: block; font-family: Arial,Verdana,Tahoma,Helvetica; font-size: 10pt;">Speech intelligibility is directly dependent on the level of background noise, reverberation time and the shape of the room. Different methods are used to evaluate speech intelligibility, the most common ones are RASTI, STI and %-Alcons.

<span style="color: #666666; font-family: Arial,Verdana,Tahoma,Helvetica; font-size: 15pt;">Speech Transmission Index (STI) <span style="display: block; font-family: Arial,Verdana,Tahoma,Helvetica; font-size: 10pt;">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.