The wind effect on sound propagation over urban areas:experimental approach with an uncontrolled sound source

Urban sound propagation is influenced by meteorological conditions, causing refraction and scattering of sound waves. An experimental study on the effect of meteorology on urban sound propagation has not been addressed yet on long-term and long-range scales. For the first time, this paper presents an approach to measure the wind effect on urban sound propagation from an uncontrolled sound source. The approach is applied to a location in Eindhoven (the Netherlands), with church bells as the source of sound. Sound is continuously measured, downwind from the sound source according to the prevailing wind direction up to 527 m from the source, and during a period of 5 months. Results of this measurement campaign show an increase of the sound pressure level of 0.4 dB, 0.8 dB, and 1.9 dB across three measurement positions per 1 m/s increase of the wind velocity over 1/3rd octave bands. Effects are stronger for lower frequencies and increases for further microphone positions. Possible future improvements of the experimental approach are discussed.