The ear is insensitive to frequency ratios

In an earlier thread on logarithmic perception and the minor triad, someone asked about the notion that intervals are not perceived as frequency ratios. This paragraph is from Richard Parncutt's "Critical comparison of acoustical and perceptual theories of the origin of musical scales", which can be found at his website. In my opinion, he is correct, regarding tonal music, but that for microtonal and spectral music, perhaps there are different aspects of music psychology...

"Octaves, 5ths and 4ths correspond approximately to frequency ratios ....But the ear is remarkably insensitive to frequ ratios between simutaneous aand successive pure tones (Allen..., Plomp et al). Western musical intervals are perceived linearly and categorically and intervals are defined by the center and bounderies of the category -- not by ratios such as 5:4 or 81:64. Intervals can vary in size by up to a semitone....These empirically based arguments cast doubt on ratio-based abstract mathematical theoris of the nature and origin of scales."