Vocalist Height system dependent?

I measured my mid range driver is at 40 inches.

Then I would think your tweeter is around 48 inches. If you sit 10 feet back with ear level at 36 inches in your comfy seat then you should have the impression of a vocalist standing at about the right height.

Remember that funny flap of skin around the ear....well it has an uncanny ability to judge the up down direction of where a sound is coming from (it also tends to cue on things in the 4K to 12K Hz range which is why sounds tend to appear to come from tweeters - even on three ways).

Also the more energy from above the plane of your ears (direct and reflected off the ceiling) the more the pinea will be telling your brain that the singer is above you.

Since music can be reverbed and deliberately engineered to give you an impression of space or height you really need to try many recordings (with no added ambience effects) to confirm.

Alternatively;

Try Tom Petty "Last Dance with Mary Jane" - lead guitar from the right and Tom Petty Dead center at tweeter height (not much added ambience on this one).

Try Tower of Power Soul Vaccination "What is Hip" - singer and band should apear to be up on stage (loads of ambience here).

Try George Bensen Weekend in LA Live "On Broadway" - Harvey Mason's drum set appears to be on a stage and you can hear him move around the set.

Perhaps, Eva is very very tall, or was singing perched up in a tall tree.

I would try some of the stereophile test cd's to check system parameters;I sure there are several other ones out there as well such as chesky.
Without really knowing the recording setup I think it would be hard to know actual postions during the recording sessions;thats why I would use test cd's that mention where the artists and instruments are placed in the soundstage.

I noticed a change in soundstage height when making changes in my sources.

Digital : swapping in a Stellavox ST-2 for my Apogee Mini-DAC raised the soundstage.

Analog : changing the stock motor of my Scheu Premier Mk II for the Pabst motor of the top-of-the-line Das Laufwerk also raised the soundstage.