FFT Spectrum should use log scale for frequency axis
The FFT spectrum currently uses a linear scale, which means that the FFT is always strongly skewed left and it can be harder to see changes over time. This can be fixed by moving to a log scale.
It's logarithmic by default, check your settings (right click on FFT spectrum).
Something seems not quite right then. I was unaware of the setting (and it is indeed set to log scale). I'll do some pixel measurements later, but just by eyeballing it, the number of pixels between ~0 Hz and 1000 Hz seems almost identical to the difference between ~21000 and ~22000 Hz.
My bad, it's not about volume, but frequency. Logarithmic requires high precision of low frequencies.
Low priority anyway.