- Report #: NT TR 478
- Approved: October 2001
- Author(s): Bo Søndergaard
In the period 1996 to 1998 DELTA and the Danish Shooting Association investigated the influence of extended firing sheds and shooting blinds on the noise level in the surroundings. The reason for this was that all Danish shooting ranges had to comply with the noise limits in Guideline 1/1995 from the Danish Environmental Protection Agency, which increased the need for reducing the noise.
Extended firing sheds are firing sheds with a noise-reducing front through which the shooting is conducted. In this case the front is a large, rectangular silencer at each shooting position. In the Nordic countries the noise assessment from shooting ranges is based on the A-weighted maximum noise level with time weighting “I”. This parameter is easy to measure in the field with a sound level meter and is less sensitive to background noise than equivalent noise levels. However, if the frequency spectrum of the noise with time weighting “I” must be determined, it is necessary to measure the equivalent level for at least 100 ms around the noise from a single shot and then correct the results.
In the above investigation it was not possible to obtain reliable results from octave band analysis because of the influence of background noise and a long averaging time. The results of the investigation are stated in LpA,I and are only valid for the weapon used for the experiments. The intention with this project is to improve the analysis method in order to be able to get reliable results for the insertion loss of the extended firing shed based on octave band analysis. This will make it possible to include the results in the Nordtest Method. The results prepared for an amendment to NT ACOU 099 are given in the Appendix.