In the Wikipedia summary on Lauridsen,
I note that in his formative years
he studied composition
with German expatriate Ingolf Dahl.

Dahl was himself a student and performing colleague of
composer Paul Hindemith,
who also emigrated from Europe to the United States (was it Yale?).

So through Dahl alone,
Lauridsen would have had
a very solid grounding in the different classical music styles
of writing, especially for solo voice or chorus.