Why do vocal harmonies of older songs sound have that rich, “airy” quality that doesn’t seem to appear in modern music? (Crosby Stills and Nash, Simon and Garfunkel, et Al)

Question

I’d like to hear a scientific explanation of this!

[Example song](https://youtu.be/C7HP9Xkim9o)

I have a few questions about this.
I was once told that it’s because multiple vocals of this era were done live through a single mic (rather than overdubbed one at a time), and the layers of harmonies disturb the hair in such a way that it causes this quality. Is this the case? If it is, what exactly is the “disturbance”? Are there other factors, such as the equipment used, the mix of the recording, added reverb, etc?

EDIT: uhhhh well I didn’t expect this to blow up like it did. Thanks for everyone who commented, and thanks for the gold!

In: Physics

Answer 1

Some of it is the mixing/mastering. [this “Twenty Thousand Hertz” episode](https://podcasts.apple.com/us/podcast/twenty-thousand-hertz/id1171270672?i=1000450841062) and the following episode covers the differences in modern mixing/mastering, versus mixing/mastering in previous decades.

Some of it is that songs used to be recorded in a single session in a big group, yeah. There are differences in the way they were recorded, and the ways that it’s been mastered make a big difference. Same with the size and acoustics of the studio in which it was recorded.