Ex. E <br />minimum effect is +3 dB and the maximum effect is +6 dB. This means an adjustment has to be <br />+4 dB <br />adjustment should be about . This means both air conditioners, running together in the <br />The +3 dB effect is due to 2 independent noise sources and the + 6 dB effect is due to 2 identical <br />noise sources. These two air conditioners are identical models which means they should make <br />the similar noise when operating. The lower frequency hum and upper harmonics , the 60 cycle <br />AC part of the noise of the two air conditioning units should be exactly the same, in phase and in <br />time and would produce the +6 dB add effect. The high frequency noise due to fan air <br />turbulence should not be exactly the same due to the randomness of turbulent noise and this part <br />of the air conditioners should only add +3 dB. In order to resolve this, the add effect of both <br />units running is conservatively assigned +4 dB. <br />(b) Error in Distance to East Property Line <br />SSA made another mistake in that the distance between the air conditioners and the residential <br />-5 dB. <br />(c) Distance Factor Incorrect <br />SSA made another oversight. They used a Distance Factor in Table 1 of 20 Log D1/D2, in <br />when the object is idealized, a point source positioned on the ground. By studying the noise <br />r <br />the first in a long list of noise measurement s supplied. <br />plotting out or calculating what SSA proposes the noise level to be over distance and what the <br />manufacturer measured the noise to be over distance, a major discrepancy becomes apparent. <br />measurements. This discrepancy between the SSA and measured sound levels can be projected <br />over the distance to the neighboring noise sensitive property lines and the correction applied to <br />the SSA prediction. <br />Noise rating off the factory chart which contains the following info about the specified air <br />conditioning unit: AVPA48ACA. The left two columns come from the factory. The third <br />column is the SSA version of the noise level at those factory measured distances that was used to <br />th <br />predict the noise impact of the air conditioning units on the neighboring community. The 4 <br />column lists out the differences between <br />version. <br />5 <br />