L. Frank Baum was fond of Music and mentions it repeatedly in his books.
By his own testimony, Baum's favorite composer was Louis F. Gottschalk, a personal friend who composed music for several Baum stage shows and films. Baum's taste seems to have been what is often called middlebrow; he expressed skeptical views of both serious classical music and popular music. The musical pieces he imagines for Oz, like "What is Oz Without Ozma," the "Shining Emperor Waltz," and the "Ozma Two-Step," or patriotic tunes like "The Oz Spangled Banner" and "The Flag of Our Native Land," seem in line with this judgement.
Baum's Oz books feature multiple references to music of varying types. Polychrome hears the music of the spheres; she dances incessantly. While traveling together, Woot the Wanderer whistles merry tunes for the rainbow fairy to dance to.
In The Road to Oz, Chapter 8, Dorothy and her companions meet "The Musicker," a sort of human music box who constantly breathes out reedy tunes. They don't like his music, and are glad to leave him behind.
Victor Columbia Edison
Baum's most extended commentary on music can be found in "The Troublesome Phonograph," Chapter 7 of his seventh Oz book, The Patchwork Girl of Oz. That chapter features a walking talking phonograph, named Victor Columbia Edison, which comments on various musical genres. According to Vic (as the thing is nicknamed by Scraps), classical music "is considered the best and most puzzling ever manufactured. You're supposed to like it, whether you do or not, and if you don't, the proper thing is to look as if you did." The phonograph's one classical record, however, is described as a "dismal tune."
Vic also plays a ragtime piece, which also displeases: it is heard as a "bewildering" and "jerky jumble of sounds." Scraps considers ragtime "the other extreme" from classical, but dislikes both.
Vic is driven off, but returns in Chapter 11 of the same book. There, it plays a popular blues or rhythm-and-blues song, "I wants mah Lulu, mah coal-black Lulu" — which earns an irate response from its hearers. (The Shaggy Man calls the device "Mr. Phony" and drives it away again.)
It is an open question how far one should generalize about Baum's tastes from these passages. The early phonograph, with its limited sound fidelity, may well have been an annoyance to people who were otherwise fond of music. (Baum's use of the phrase "coal-black Lulu" has been judged racially offensive by modern sensibilities — yet some early blues or imitation-blues recordings, long forgotten today, perhaps were crude enough to justify ridicule.)
Baum's urge to ridicule the pompous side of classical music appreciation is not incomprehensible; Mark Twain did the same thing. Indeed, Baum and Twain shared one specific target: Richard Wagner. (Twain famously asserted that Wagner's music "is better than it sounds.")
Richard Wagner (22 May 1813 – 13 February 1883) was arguably the most famous and controversial composer of his era. Baum refers to him as "Vogner" in John Dough and the Cherub. In Chapter 6, "The Freaks of Phreex," the "fluffy-haired" composer Tietjamus Toips believes he is "better than Vogner himself!" Toips asserts that "Some folks can understand Vogner a little. No one can understand me at all!"
In The Magical Monarch of Mo, "The First Surprise," Baum specifies that the lightning seen in the Land of Mo "resembles the most beautiful fireworks," while "the thunder is usually a chorus from the opera of Tannhauser."
In The Woggle-Bug Book, the protagonist falls in love with a woman's "Wagnerian plaid" dress. Here, the term "Wagnerian" may simply mean loud and garish.