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.    the curve is never more than 8 dB below the NIC contour in and 1/3 octave band; and

2.    the sum of the deficiencies below the contour over the 16 1/3 bands does not exceed 32 dB.

When the NIC contour is shifted to meet these criteria, the NIC rating is given by the value of the contour at 500 Hz.

Job Reference

1.    Ever Construction Co. Ltd.
Field Noise Reduction Measurement of Curtain Wall at 158-160 Waterloo Road according to ASTM E-336 and ASTM E-413.

2.    Builders Federal (Hong Kong) Ltd.
Field Sound Transmission Class Measurement at Conrad Hotel Ball Room LL4 according to ASTM E-336 and ASTM E-413.

3.    Flexible Space Systems Ltd.
Field Noise Isolation Class Measurement of Partition at Olympic Station HSBC Center according to ASTM E-336 and ASTM E-413.

4.    Builders Federal (Hong Kong) Ltd.
Field Sound Transmission Class Measurement for Party Wall at CityPlaza according to ASTM E-336 and ASTM E-413.

5.    Kelly Construction Co. Ltd.
Field Sound Transmission Class Measurement for Party Wall at CityPlaza according to ASTM E-336 and ASTM E-413

6.    Tak Woo Hong Kong Engineering Ltd.
Field Sound Transmission Class Measurement for Acoustic Door at CityPlaza according to ASTM E-336 and ASTM E-413

7.    Golden Eon Engineering Ltd.
Field Sound Reduction Index Measurement for Aluminium Window at Regal Airport Hotel according to ISO140-4.

8.    Eurasia Architectural Products Ltd.
Field Noise Isolation Class Measurementt for Movable Partition at Hong Kong Sanatorium & Hospital  according to ASTM E-336 and ASTM E-413.

9.    Sellmax Limited.
Field Noise Isolation Class Measurement for Movable Partition at  Heng Seng Bank Headquarter according to ASTM E-336 and ASTM E-413.