The Beatrice Welles who was devoted to Orson Welles insisted that he spend a great deal of time on the violin as a child.

Could that have influenced his overall artistic development?

In the current edition of Harpers, Dr. Oliver Sacks is quoted:

I think you're correct. Of course in this instance the so-called Mozart effect--often reduced in practice to the simplification that merely hearing some gentle classical era music will spur on certain areas of brain development--is to be distinguished from developing a life with music, as Mr. Welles did, or was led to do. I feel strongly that his early experiences with music were rather formative and influential on the rest of his life. This applies i think to the development of his aesthetics, as well as his intellectual capabilities. I'm thinking of the linguistics in particular.

In a purely music sense, i think the man had developed a great ear. "...a man of great musical culture", as Hermann said. Something i've noted about Welles is that he seems to have been open to wider musical influences in his pictures than most directors / film composers were, particularly within the large tradition of western musical practices that are imprecisely named "Classical". Clearly he was deeply involved with the creation of scores to his films, and was able to find some great collaborators. I really wish i was a fly on the wall when he and Hermann discussed music. It seems that Welles encouraged Hermann to invest Kane with a variety of rich musical gestures, many traceable back to folks like C. Ives, Debussy, Schoenberg, Webern, Berg. The significance here is that these musical languages were still considered quite new at the time (and indeed are still considered to be new / too much by some people). Hollywood music was generally going strongly with very 19th Century idioms (up through R. Strauss and Mahler) until this point. There came increasingly more references to idioms of the great modern composers, but these are generally to my ear almost always so inept and watered down as to be parody, Hermann being the only major film composer around this time to use them with dignity and authenticity. Look at what happened to parts of Ambersons when the score was no longer kept sacred--they bring it back to hackneyed "tender" harmonically 19th century music. Welles was using works of G. Antheil for "the Lady from Shanghai" before the clichéd score was appended...I only wish that the scenario for 2001's music--the score being abandoned for prewritten works--had had a precedent here.