I'm using PPI's Prep Manual 5.0 to prepare for PPD. The section on acoustics sound intensity level has been confusing me (pages 19-13 & 19-14) because the way PPI writes the Common Log as used in Equation 19.6 for Addition of Decibels of Uncorrelated Sound is not clear. Common Log is log base 10; however their equation also uses 10 as a multiplier...which is confusing. To clarify in the hopes this is useful to others:
- PPI writes "10logn" as part of the equation.
- This part of the equation actually means "10 x the common log of n"
- In other words, take the number of sources and multiply it by log base 10; then multiply that by 10; then go on with the rest of the equation.
I'm not good as math so this has been confusing to me and taken a solid hour+ to figure out. I hope this helpful to others.
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