Alternative procedures for environmental noise assessment

摘要

It is simple algebra that a noise of 85 dB(A) lasting a minute during daytime has the same equivalent level, as a noise occurring 300 times for a minute with a level of 60 dB(A). This contradiction between noise duration and the public reaction to be expected will be examined using observations in the neighborhood south of the Frankfurt Airport before and after the opening of an additional landing strip. Based on this, the air craft noise situation resulting from the present and future air traffic at Zurich airport in the black forest area adjacent to the Swiss border is studied, comparing the concept of energy equivalent levels, loudness equivalent level and the daily duration during which air craft noise can be heard in view of measured background levels of less than 25 dB(A) in this area. To estimate the changes in loudness and the loudness equivalent level the averaged statistical distribution of the observed levels and the respective spectral structure is needed. This includes spectral structure of the background noise. As well as, of the sources under consideration, as it can be provided, using the hourly percentiles L_(90),L_(50),L_(10) and their percentile spectra. Using this, the loudness equivalent levels can be calculated. As can be seen from the increase in air traffic until 2030 at Zurich airport, the increase of the energy equivalent level may be 1 dB compared to 4.2 dB to the loudness equivalent level. This means that the loudness reacts far stronger to the increase of flight events.