I can't carry a tune in a bucket, but I did take music lessons (voice and violin) and had one music teacher that would sing our National Anthem A Cappella at high school football games without any help from a sound system.
Of course the crowds back in the 50's showed some respect for the song and stood with their hand over their heart and didn't talk during its performance, but being able to project your voice over a 100 yards is difficult, much less being able to do so in a manner that is intelligible at the receiving end.
Unfortunately, he wasn't able to teach me how to match the tones coming out of my mouth with the tones in my head, but he did teach me how to make myself heard in a noisy crowd.
Along another vein, the ears of the youth aren't the same as the ones possessed by we older folks, and not because of all the shooting we've done without proper hearing protection either.
I've got Marty singing "Big Iron" on both 45 and 33 vinyl, and on CD. The 45 and 33 sound about the same, but the CD is quite a bit different.
From what I can determine, the CD was re-mastered from the original tapes and whoever was on the mixer board cranked up the mid and high ranges, something I've noticed with nearly every recently re-mastered older song I've heard.
Fortunately, a little tweaking with inexpensive music editing software is enough to make them sound okay to my old ears.
John