Comparing two approaches for outdoor ambient noise level measurements

In ambient community noise measurements, two possible setups involve an elevated microphone or on the ground [ANSI 12.9-2005/Part 2]. This study compares the elevated and ground-based microphone measurement approaches, particularly for low-frequency wind noise contamination. Wind speed measurements were made at heights of 0.15 m and 1.5 m, and one-third octave spectral histories were recorded simultaneously at the ground and at 1.5 m. The acoustical measurements both used Larson Davis 831C sound level meters, but the elevated microphone setup employed a commercial outdoor windscreen, whereas the ground-based setup utilized a larger reticulated foam windscreen. The measurements, each with durations between 1.5 and 4 h, were repeated at several locations. The results show the ground plate setup is preferable for obtaining wideband spectral measurements for two reasons. First, the wind speed is lower near the ground. Second, for the same wind speed, the larger windscreen yields superior wind noise rejection. These observations are quantified and discussed, and connected to expanding the available noise database for a machine-learning model for soundscape prediction. [Work supported by a U.S. Army SBIR.]In ambient community noise measurements, two possible setups involve an elevated microphone or on the ground [ANSI 12.9-2005/Part 2]. This study compares the elevated and ground-based microphone measurement approaches, particularly for low-frequency wind noise contamination. Wind speed measurements were made at heights of 0.15 m and 1.5 m, and one-third octave spectral histories were recorded simultaneously at the ground and at 1.5 m. The acoustical measurements both used Larson Davis 831C sound level meters, but the elevated microphone setup employed a commercial outdoor windscreen, whereas the ground-based setup utilized a larger reticulated foam windscreen. The measurements, each with durations between 1.5 and 4 h, were repeated at several locations. The results show the ground plate setup is preferable for obtaining wideband spectral measurements for two reasons. First, the wind speed is lower near the ground. Second, for the same wind speed, the larger windscreen yields superior wind noise rejection....