Measurement of reverberation gain in an urban environment.

Multipath propagation within an urban area introduces a specific type of reverberation in response to sound excitation. That appearance affects the level of ambient noise produced by strong sound sources. In this paper, the signals recorded during the 1999 bombing of Belgrade were used to analyze the characteristics of reverberation in that urban environment. Six recorded signals were selected among more than 50 explosions recorded at that time. Due to the impulse nature of sound sources, the recorded signals represent the impulse responses of that area. The measured reverberation time T30 is about 7 ± 1 s in octaves between 31.5 Hz and 1 kHz. There is a variation of decay slope in time that is verified by differences between values of T10 and T30. The reverberation gain calculated from recorded signals is 2-7 dB, depending on the global position of the sound excitation point as well as its micro-location according to its position among the surrounding buildings. A variation of gain over octave bands is in the interval of approximately 3 dB. Information about reverberation gain in urban environment can be useful in a quick estimation of noise level produced by strong sound sources in a large area of urban environment.