I have some coefficient values i.e. 74.9, 81.3, and 80.5 at frequency centers 63, 160 and 400 Hz. The values are 1/3 octave band values. I would like to convert them to the 1/1 octave band values. Can someone suggest how to do that?
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2 Answers
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If I'm understanding your question correctly, you want to sum up levels given as 1/3 octave bands into 1/1 octave band resolution. This can be accomplished by decibel summation:
$L_\Sigma = 10 * log(10^\frac{L1}{10} + 10^\frac{L2}{10} + 10^\frac{L3}{10})$
Where $L$ are levels in dB.
Please see here for an online summation tool.
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The short answer is, you cannot calculate octave-band levels from single 1/3-octave band levels only. For example, in order to calculate the 63-Hz octave band level, you must know the the 50, 63 and 80-Hz 1/3-octave levels, and add them according to the formula for decibel summation as above.
