The ISO 9614-1: Determination of Sound Power levels using sound intensity: Part 1 - measurement at discrete points is an international standard for sound power.
The standard is designed to enable sound power measurements in field (and lab) environments where it is difficult to move the device under test (DUT) into a specially designed acoustic environment, or where support equipment prevents use of traditional sound pressure methods.
By measuring sound intensity on a hypothetical surface, the DUT may be isolated from the rest of the acoustic environment. It is therefore possible to measure in an environment where the extraneous noise energy is louder than the DUT.
In the part 1 of ISO 9614, the hypothetical surface is divided into segments, each representing a measurement point. One measurement is performed per measurement point, and the total sound power level is determined by summing the partial sound powers from each position.
The standard operates with the three well-defined ISO accuracy grades:
- Precision grade [LW(A) ± 1.0 dB]
- Engineering grade [LW(A) ± 1.5 dB]
- Survey grade [LW(A) ± 4 dB]
Precision and engineering grade has stricter requirements than the survey grade, but has well-defined uncertainty constraints for each 1/3 octave band, while survey only defines a A-weighted uncertainty.
To guarantee the uncertainty, a several field indicators are defined. Several checks applies to these field indicators. The Nor145 automatically calculated the field indicators and checks if the measurements are valid.