Since I installed MC 11.1 I have been interested in the new real-time spectrum analyzer.
I have played with it a bit using
Fred Nachbaur's test signals, and I figured out better how MC's spectrum analyzer works.
The frequency scale of the analyzer is
not linear, as I first guessed. It behaves
more or less like a third-octave analyzer, but it is not really a standard third-octave analyzer, which has only 31 bands from 20 Hz to 20 kHz. There are 32 bars in MC's analyzer, and the upper frequency is limited to 16 kHz. The number 32 was clearly chosen because it is programmer-friendly (it is a power of 2), and to double the 16 bars in Windows Media Player. But the 32 bars in the analyzer do not exactly match with the bands in a standard third-octave analyzer. They are wider in the low part of the spectrum (20 Hz and 25 Hz show up in the same bar) while the are narrower in the high part of the spectrum, so that 4 kHz and 5 kHz are have a bar in between, and are not adjacent as in a standard third-octave analyzer). That gave me the (wrong) impression that the scale was more linear than logarithmic.
I also pointed out that it seemed that the analyzer introduced a +3dB/oct boost, because a pink noise would show a flat spectrum. The remark would have been correct for a linear frequency scale. But for a third-octave analyzer (with constant Q bands) it is correct that a pink noise exhibits a flat response. Pink noise is defined as a random signal with the same power content in each octave. So as we increase the center frequency of the band, the width of the band increases too. For every octave, the width of the band doubles. The power content, on the other hand, decreases by 3 dB (halves) per octave. So the power contained in each band remains the same. The spectrum analyzer is thus behaving correctly.
Audio-conscious users (audio geeks) would prefer to have each bar in the analyzer to correspond to a standard band in a third-octave analyzer (there are 31 bands from 20 Hz to 20 kHz, but since MC's analyzer limits its frequency range to 16 kHz, only 30 bars remain).
A global level meter should go in the Action Windows instead, as I pointed out in
another thread.
Any thoughts?