1 Scope
This part of ISO 140 specifies two series of methods (element methods and global methods) for measurement
of the airborne sound insulation of façade elements and whole façades, respectively.
The element methods aim to estimate the sound reduction index of a façade element, for example a window. The most accurate element method uses
a loudspeaker as an artificial sound source. Other, less accurate, element methods
use available traffic noise. The global methods, on the other hand, aim to estimate
the outdoor/indoor sound level difference under actual traffic conditions. The most accurate global methods use the actual
traffic as sound source. In addition, a loudspeaker may be used as an artificial sound
source. An overview of the methods is given in table 1.
The element loudspeaker method yields an apparent sound reduction index which, under certain circumstances [e.g. taking account of measurement precision
(see 7.1)], can be compared with the sound reduction index measured in laboratories in accordance with ISO 140‑3 or ISO 140‑10 . This method is the preferred method when the aim of the measurement is to evaluate
the performance of a specified façade element in relation to its performance in the
laboratory.
The element road traffic method will serve the same purposes as the element loudspeaker
method. It is particularly useful when, for different practical reasons, the element
loud...