Interesting presentation on sound

The referenced link is to an interesting presentation by Nobel Prize winning physicist Richard Feynman just over 50 years ago. Please believe me when I state that I do NOT sit around studying physics in my spare time however Feynman was a maverick, always searching for simple ways to explain the physical world.

In this presentation, Feynman briefly explains mathematically how a sound is deemed pleasant and the converse as it relates to harmonics and the ear in relation to the physical world. Something really cool though is the last paragraph of the presentation refers all too briefly to light and its harmonics, specifically how a "red light" laser that passes through glass carries "blue light" harmonics. Lasers were barely understood in the early 1960's.

Anyway, I wonder if light harmonics has anything to do with why some digital is unpleasant to some listeners? could this be why the digital transport quality is so important and further explain why the computer through an alternate digital delivery method (instead of laser light of a cd transport pickup, using a USB or other method of non light digital transmission) has apparently taken hold as a preferential method? Finally, is this what analog purists have been saying all along?

Enjoy the article. Amazing this was communicated over 50 years ago, long before digital music was envisioned as a delivery medium.
The reason red laser light is blue when it passes through glass or polycarbonate is due to the refraction of light in a medium, I.e., the wavelength in glass is shorter. When the light comes out the other side of the glass it is red. This doesn't explain why CDs can sound unpleasant, but there are a lot of reasons why they could sound unpleasant, such as scattered red laser light.
I belive the "unpleasantness" often has to do with inferior filtering that is is or was used, both in the analog-to-digital and digital-to-analog conversions. We also now know more about, and how to control, processes such as jitter and pre-ringing, which were not well understood in the early 80s when the medium was first commercialized. It arrived to us partly baked via Philips and Sony, and has since come a long way in improvements. I am a devout vinyl fanatic, but I do enjoy well-recorded CDs and listening to downloaded digital files and streaming via my Mac into a Qyred 4 Sound DAC2.