In this Quora answer
the answerer claims
it is important to distinguish between pure tones, that is, simple sine waves, and real tones, such as those produced by a musical instrument or human voice, which in fact contain a (mostly) harmonic series of overtones of varying amplitudes. Psychoacoustic experiments on untrained listeners involving the perceived consonance of pairs of pure tones yields a surprising result. Consonance decreases rapidly as the pitch interval increases from zero (that is, a single tone), as one might expect from our experience with real tones, reaches a nadir at about one semitone, and then reaches nearly 100% again near a minor third. However, consonance is not perceived to decrease again as the interval is increased. That is, all pure tones that are separated by intervals of greater than a minor third are equally consonant.
I googled a bit and could not find evidence for this claim. It is an interesting claim and I would like to read more about the reasoning behind this.
Why might this be? Johnston suggests that the answer may have something to do with the bandwidth of the frequency-tuned cochlear cells that detect sound in the inner ear. Two tones separated by larger than the bandwidth of a cochlear cell do not interfere in the ear at the site of transduction, whereas tones within the bandwidth do.
But again, I am unsure why a google search did not turn up more information. He cites a book and, if necessary, I will track it down at my library and read it, but I decided to ask here first to see if anyone has further information before resorting to that.
Are all pure tones that are separated by intervals of greater than a minor third are equally consonant? Why?