I was fooling around with the spectrogram a bit more. I will throw up a couple screenshots to help illustrate something about the spectrograms. This is a spectrogram of a full scale 30 Hz since wave depicted in a linear scale:
Now here is that same sound depicted by the spectrogram on a logarithmic scale:
If you look carefully, you will see that total available frequency band shown is 10 to 225 Hz in both pictures. The logarithmic scale really 'blows up' the presentation of deep bass, not that it is actually louder. When I look at stuff on the spectrogram, I am usually looking at what is happening in deep bass, and the logarithmic scale gives more detail there. Also, humans hear pitch more on a logarithmic scale than linear. It's not really inaccurate because more energy is needed to sustain the same SPL at longer wavelengths anyway. However, it might be easy to overestimate the amount of deep bass content from these pictures by just looking at logarithmic scales. Let's take another look at that chunk of track from the Halloween tune- but on a linear scale:
Compare that to the spectrogram from the first post. One thing about the linear scale is gives a clearer look at the harmonic relationships of the sound, since the energy bands on a linear scale are evenly spaced.
