Evaluation of ANSI low frequency measurement standard S12.9 part 7 in light of current research

ANSI S12.9 Part 7 (2016) Measurement of Low-frequency Noise and Infrasound Outdoors in the Presence of Wind and Indoors in Occupied Spaces was developed over 2-3 years and was a much needed guide to standardize the measurement of low frequency sound and infrasound. Since then, research has advanced what are now considered best practices, and technology has advanced to make instrumentation available to consultants and researchers to help solve several limiting issues in measurements. This paper provides a review of the standard and recommends improvements to the techniques used in the measurement of low frequency-infrasound outdoors. These improvements include better assessment and understanding of wind noise, the importance of sensor placement, and advances in transducers, wind screening, arrays and calibration. The information provided includes best practice with a conceptual understanding of the interaction with the environment in low frequency-infrasound measurement; references are provided for a deeper dive into each topic.