Acoustics_Vocabulary

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.
 * Articulation Class (AC) **

**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.

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

RASTI is an objective way of measuring speech intelligibility.
 * Rapid Speech Transmission Index (RASTI) **

Measured in dB (deciBel). dB is measured at different frequencies.
 * Sound strength (dB) **

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
 * Speech Transmission Index (STI) **