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

Vocals were often recorded much further off the mic back then 1-2′ rather than 6″.
Also not everything was pitch corrected and an amount of tuning variation between harmonies can make them sound thicker and richer.

Edit: auto correct hates me