Complied with: ASTM E336, ASTM E413, ISO 140-4
There are many relevant standards for field measurement of building material sound isolation performance, the measurement result may be presented with different unit or naming. The command use standards and corresponding result naming is showed in following table:
The measurement procedures and calculation methods are slightly different for each presenting unit, however the requirement for measurement equipment are the same. Our laboratory have all type 1 and well calibrated instruments which complied with ISO 140-4 and ASTM E336, the measurement result presenting unit is depended on the client request.
Detail of NIC Measurement
The Noise Isolation Class (NIC) measurement was carried out according to ASTM E-336 'Testing Method for Measurement of Airborne Sound Insulation in Buildings' and the calculation was carried out according to ASTM E-413.
NIC of the test specimen was determined by comparing the noise levels sampled inside the source and receiving rooms between which the test specimen separating them. Sound measurement was carried out inside the two rooms. The loudspeaker (OmniPower Sound Source) is fed with white noise in 1/3 octave band. The averaged sound pressure level was measured in 1/3 octave band frequencies, from 100 Hz to 5000 Hz. The microphone positions are located at 1 m in front of the test specimen.
A single number descriptor, NIC is used to facilitate the performance comparison of different element. To determine the NIC for a particular element, a curve fitting technique is used to fit the calculated 1/3 octave band .
NIC contour consists of a horizontal segment
from 1250 Hz to 4000 Hz, a middle segment increasing by 5 dB from 400
Hz to 1250 Hz and a low frequency segment increasing by 15 dB from 125
Hz to 400 Hz. The NIC rating of an element is determined by plotting the
1/3 octave band of the element and comparing it with the NIC contour.
The NIC contour is shifted vertically until the NR curve fall mainly below
the contour and the following criteria are met:
1. Ever Construction
9. Sellmax Limited.