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Gas Turbine Handbook : Principles and Practices

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Appendix C 383<br />

Appendix C-12<br />

Overall A-weighted Sound<br />

Level Calculation<br />

An example calculation of the overall A-weighted level is<br />

presented. It is based on having a set of octave b<strong>and</strong> levels that are<br />

un-weighted; that is, there is no filter weighting applied to the measurement.<br />

If the levels are already A-weighted then skip to the summation<br />

equation (C.12-2) that follows Table C.12-2.<br />

Table C.12-1 Octave B<strong>and</strong> Sound Pressure Levels (SPL), dB<br />

Octave B<strong>and</strong> Center<br />

Frequency, Hz<br />

Sound Pressure Level, dB<br />

(Measured or Calculated)<br />

31.5 74.0<br />

63 66.0<br />

125 71.0<br />

250 61.0<br />

500 60.0<br />

1000 75.0<br />

2000 82.0<br />

4000 80.0<br />

8000 87.0<br />

Next, convert the sound pressure levels to octave b<strong>and</strong> A-<br />

weighted levels by:<br />

L A = Lp + A – wt dB<br />

(C.12-1)

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