This part of ISO 16283 specifies procedures to determine the airborne sound insulation of façade
elements (element methods) and whole façades (global methods) using sound pressure measurements.
These procedures are intended for room volumes in the range from 10 m3 to 250 m3 in the frequency
range from 50 Hz to 5 000 Hz.
The test results can be used to quantify, assess, and compare the airborne sound insulation in
unfurnished or furnished rooms where the sound field can or cannot approximate to a diffuse field. The
measured airborne sound insulation is frequency-dependent and can be converted into a single number
quantity to characterize the acoustic performance using the rating procedures in ISO 717-1.
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. A loudspeaker can be used as an artificial sound
source when there is insufficient level from traffic noise inside the room. An overview of the methods is
given in Table 1.
The element loudspeaker method yields an apparent sound reduction index which, under certain
circumstances, can be compared with the sound reduction index measured in laboratories in accordance
with ISO 10140. 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 loudspeaker method cannot be
used. These two methods will often yield slightly different results. The road traffic method tends to
result in lower values of the sound reduction index than the loudspeaker method. In Annex D, this road
traffic method is supplemented by the corresponding aircraft and railway traffic methods.
The global road traffic method yields the real reduction of a façade in a given place relative to a position
2 m in front of the façade. This method is the preferred method when the aim of the measurement is to
evaluate the performance of a whole façade, including all flanking paths, in a specified position relative
to nearby roads. The result cannot be compared with that of laboratory measurements.
The global loudspeaker method yields the sound reduction of a façade relative to a position that is 2 m
in front of the façade. This method is particularly useful when, for practical reasons, the real source
cannot be used; however, the result cannot be compared with that of laboratory measurements.
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