Plot Spectrum: Lower amplitude limit

When running Audacity with default preferences, opening “Show spectrum” shows a fixed lower limit at -90 dB, even if there is spectral content below this level. In most situations, you can’t even see the noise floor. By chance I found out that changing “Preferences → Interface → Meter dB range” to something lower than -90 dB, the lower limit in “Show spectrum” will be changed as well.

IMHO, this is a very strange “feature”. I call this “feature” because it was apparently done on purpose (see FreqWindow.cpp and search for dBRange).

Wouldn’t it be better to make this independent of the “meter dB range”? Isn’t it strange to plot the spectrum only down to -90 dB just because the monitoring dB range minimum is set to a value greater than -90 dB?


  • remove the -90 dB limit, i.e. set the lower limit to the lower limit of the content (as done for meter settings below -90 dB)
  • add the possibility to change the lower limit in the plot window
  • add a new option in the preferences to set this lower limit

what do you think?

I assume that you are referring to “Plot Spectrum”, so I have changed the topic title accordingly.

Personally, I’m not a fan of the auto-scaling. I would much prefer that it simply defaulted to the last used size and allowed the user to scale as they wish.

Yes, of course, “Plot Spectrum”, I’m sorry.

I would also tend to allow scaling to the user.