1004 59TH PL SW 2016-01-01 MF Import

Noise Assessment: Broadway Apartments Project Michael R. Yantis Associates Inc., P.S. Page 2 decibels, indicated as "dBA". The sound level measurement in dBA is weighted to emphasize the loudness of high pitch sounds, conforming with the human ear's perception of loudness. For each short term measurement, a simultaneous measurement was also made at the location of the original 24-hour measurement, referred to as Location A. The Ldn foci each of the short term measurement locations was estimated by comparing each short terra measurement to the measurement made simultaneously at Location A, where the Ldn is known. For example, the short-term measured noise level at location B was 6.5 dB lower than the noise level measured simultaneously at location A. The Ldn at location B can thus be expected to be less than the Ldn measured at location A by 6.5 dB. Since sound is measured on a decibel scale, the loudness of sound is not proportional to the decibel level. For cxampic, 110 dBA is not 10 percent louder than 100 dBA. Loudness comparisons are scaled from differences in sound level measurements, approximately as follows: ■ 3 dBA difference in sound levels is a perceptible difference ■ 5 dBA difference is significantly louder (or softer) ■ 10 dBA difference is twice as loud (or soft) Using this guideline, a noise source measured as 75 dBA is twice as loud as one measured as 65 dBA. MEASUREMENT RESULTS Measurement results, in terms of average and maximum noise levels, and the 24 hour day- night equivalent noise level (Ldn), arc as shown in Table 1. Short-term measurements at four locations adjacent to the tight of way are shown in Table 2. Current average noise levels at the home sites, which will range from 2 to 8 feet below the roadway, will be approximately equal to the 56 dBA (Ldn) levels at Locations C and D, listed in the next to last column of Table 2.