I get a laugh every time I read that. I love the fact they never mention that sound travels in waves. What happens to waves when they interact with each other? They distort each other. Yes we only hear up to the 20k range. Does that prevent a sound that we can not hear from distorting a sound that we can? The answer is no. So, YES higher frequencies that we can not hear do influence sounds we hear all the time.
AES E-Library » Audibility of a CD-Standard A/DA/A Loop Inserted into High-Resolution audio Playback
BAS Experiment Explanation page - Oct 2007
"[Engineering Report] Claims both published and anecdotal are regularly made for audibly superior sound quality for two-channel audio encoded with longer word lengths and/or at higher sampling rates than the 16-bit/44.1-kHz CD standard. The authors report on a series of double-blind tests comparing the analog output of high-resolution players playing high-resolution recordings with the same signal passed through a 16-bit/44.1-kHz “bottleneck.” The tests were conducted for over a year using different systems and a variety of subjects. The systems included expensive professional monitors and one high-end system with electrostatic loudspeakers and expensive components and cables. The subjects included professional recording engineers, students in a university recording program, and dedicated audiophiles. The test results show that the CD-quality A/D/A loop was undetectable at normal-to-loud listening levels, by any of the subjects, on any of the playback systems. The noise of the CD-quality loop was audible only at very elevated levels."
You aren't the only one who chuckles.