Audibility of error (and sound in general) depends on what other audio is playing at the same time, with both frequency domain and time domain effects:
Here's a two-part lecture with audio demonstrations by Bernhard Seeber of the Audio Information Processing Group at the Technical University of Munich:
A simple weighed frequency domain error calculation is not very useful for comparing lossy audio codecs, because effectively exploiting auditory masking to hide the errors is a major factor in codec quality.