Is the FFT magnitude of two audio signals when played together the sum of their individual FFT magnitudes across frequency bins? Note I'm talking only about the magnitude, ignoring phase.
For instance, if two pure signals of sine wave of the same frequency but 180 degrees off phase are played simultaneously, would the magnitude of the FFT at said frequency be double that of a single signal or 0?
I believe it's the latter but I want to confirm.
Thanks