2025 02 03 Acoustical Evaluation

PN Restaurants -2- 3 February 2025 2.0 AMBIENT SOUND PRESSURE LEVEL MEASUREMENTS 2.1 Proposed Site On Tuesday, 20 June 2023, the sound levels at the site were continuously monitored over a 24 hour period beginning at 8:00 A.M. Figure 1, at the end of this letter, shows an aerial view of the site with the acoustical measurement location identified. The measured 30- minute ambient Leq1, L102, L503, and L904 overall A-weighted5 sound levels are presented in Figure 5, at the end of this letter. Sound sources that contributed to the ambient sound pressure levels at the proposed site during the measurement included traffic, wildlife, and aircraft. 2.2 Data Acquisition and Analysis The measurements at the proposed site were performed using a Rion Type NL-52 precision sound level meter, equipped with a Rion Type US-59 microphone. The analyzer automatically recorded statistical A-weighted and one-third octave band sound pressure levels and stored the results in memory for later retrieval. The microphone was mounted on a tripod at a height of approximately 5 feet above grade, and a windscreen was placed over the microphone for all measurements. The system’s calibration was verified in the field before and after the measurements using a Brüel & Kjær Type 4231 acoustical calibrator. The stored data was later downloaded and transferred to a spreadsheet for evaluation. Copies of the NIST traceable calibration certificates for the sound level measurement equipment are available upon request. 1 The Leq represents the energy-averaged continuous sound pressure level during the measurement period. 2 The L10 is the sound pressure level exceeded 10 percent of the time, and represents the transient sound pressure levels during the measurement period. 3 The L50 is the sound pressure level exceeded 50 percent of the time during the measurement, and represents the median sound pressure levels during the measurement period. 4 The L90 is the sound pressure level exceeded 90 percent of the time, and represents the continuous sound pressure levels during the measurement period. 5 A-weighting, noted as dB(A), is a standardized sound level meter setting having a frequency characteristic similar to the human ear/brain frequency sensitivity.