Ecler CKL SERIES - Manual (Page 14)

14
Following table shows recommended RT
mid
values for different types of rooms:
ROOM TYPE RT
MID
, fully occupied room (en sec.)
Conference room 0.7 – 1.0
Cinema theatre 1.0 – 1.2
Multifunctional room 1.2 – 1.5
Opera theatre 1.2 – 1.5
Concert Hall (chamber music) 1.3 – 1.7
Concert Hall (symphonic music) 1.8 – 2.0
Church (organ and choral music) 2.0 – 3.0
Radio voice booth 0.2 – 0.4
Recommended RTmid value ranges for various types of rooms.
Calculation of RT
60
Although several methods for the calculation of reverberation time exist, the most widespread is the classic
Sabine equation:
A
V
RT 161 . 0
=
Where V is the volume and A is the total absorption of the room.
8.3. Speech intelligibility
The main objective when designing a room destined for speech reproduction, be it with or without
electroacoustic reinforcement, is that the message must be clearly understood by all the audience.
Many research efforts have been put in subjectively determining the degree of intelligibility inside a
room. In the early 70s, the Dutch acoustician V.M.A. Peutz carried out a comprehensive research which
gave place to an equation that puts speech intelligibility as a function of room acoustics. The parameter
is called %ALcons.
Following table shows a range of %ALcons values and their corresponding subjective intelligibility
degree, according to Peutz’s equation:
Subjective intelligibility degree, according to Peutz.
%ALCons Subjective intelligibility degree
Between 0 y -3 % Excellent
Between -3 y -7 % Very good
Between -7 y -10 % Good
Between -10 y -15 % Acceptable
Between -15 y -30 % Poor
Less than de -30% Unacceptable