Table 2.2 of HN 33:2026 introduces the Ld, Lv, Ln and Ldvn indicators for road-traffic noise.
This is a significant change for noise-measurement laboratories because it creates uncertainty regarding measurement duration and the practical determination of these indicators. Short-term measurements of 10–60 min are no longer sufficient where Ld, Lv and Ln must be determined and assessed and the Ldvn indicator calculated from them.
This change directly affects:
If exceedances are identified under the selected methodology, clients or supervisory authorities may reasonably question whether the results are representative. In such a case, laboratories may have to repeat the measurements, and the results may differ from the initial assessments.
It would be in the interests of all parties to obtain a clear and uniform interpretation of the application of HN 33:2026, as the current wording leaves substantial scope for differing interpretations.
