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PRACTICE / Sound intensity and decibels

Add intensities before decibels

At one observation point, either of two mutually incoherent sound sources alone gives an intensity level of 60 dB relative to the same reference.

Find the level when both operate together.

Organize the givens & assumptions
  • Each source alone: 60 dB
  • Intensities add
  • log₁₀2 = 0.3010

Independent sources with uncorrelated phases; no change to either source when the other operates. Use log₁₀2 = 0.3010.

  1. A120 dB120\ \mathrm{dB}
  2. B60 dB60\ \mathrm{dB}
  3. C66.020 dB66.020\ \mathrm{dB}
  4. D63.010 dB63.010\ \mathrm{dB}

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