# How to represent ratio between harmonics in audio spectrum

I was provided a report where the amplitudes of spectral harmonics have been extracted from several audio files. The amplitudes have been extracted using Audacity's spectrum visualizer, where the spectrum is provided in dB. I want to compute the ratio between the amplitude of the fundamental and the amplitude of each harmonic. Does it make sense to perform a ratio in dB or should I use the difference between amplitudes? Thank you.

• I would use a difference in log domain and ratio in linear one. – jojek Sep 25 '15 at 10:05
• Recall that a dB is just the logarithm of a ratio, multiplied by 10. We use dBs because they help us compare 2 quantities that may have largely different values. So in your case, if you see that those differences are huge, maybe you would prefer to use dBs. I would. – vaz Sep 25 '15 at 10:34
• @Francesco Did you receive a satisfactory answer to your question? – Richard Lyons Sep 25 '15 at 11:45
• What are you trying to do? What is the goal of this analysis? – endolith Sep 25 '15 at 13:54
• I am analysing several instruments by comparing the relative amplitude of each harmonic (for a specific note), and I want to represent it in the most appropriate way. The available data (harmonics amplitude) are in dB because they have been extracted using Audacity Spectrum analyser – firion Sep 25 '15 at 14:37

• In any case if you have the "dB" of the harmonics and the "dB" of the fundamental - assuming both are on the same scale - then you can compute the distortion in dB as dbFund - dBHarms. – jaket Sep 25 '15 at 11:03