Short answers, pulled from the story.
J. R. R. Tolkien was both a philologist and an author of high fantasy who stated that all his work was fundamentally linguistic in inspiration. The invention of languages served as the foundation for his stories rather than the other way around. He believed human sub-creation mirrored divine creation through thought and sound bringing a new world into being.
Around 1900 multiple artistic and literary movements stressed language and the sound of words including Italian Futurism, British Vorticism, and the Imagism of Ezra Pound. Nonsense poets such as Lewis Carroll with his Jabberwocky sought to convey meaning using invented words during the late 19th century. Edward Lear also sought to convey meaning using invented words which suggested that meaning could be conveyed even with words that were apparently nonsense.
The linguist Allan Turner writes that the sound pattern of a language was the source of a special aesthetic pleasure for Tolkien. In his essay about constructing languages A Secret Vice Tolkien wrote that the person inventing a language must address the fitting of notion to oral symbol. This focus on phonetic fitness placed him at odds with conventional linguistic theory because he valued word-form in itself more than any other department.
Real names tell you the story of the things they belong to in my language according to the Ent Treebeard in The Two Towers. When Tom Bombadil named something like the ponies that the Hobbits were riding the name stuck and the animals responded to nothing else for the rest of their lives. Knowledge of a true name might give one power over that thing or being within the narrative context.
The linguist Joanna Podhorodecka examines the lámatyáve a Quenya term for phonetic fitness of Tolkien's constructed languages by comparing two samples of Elvish and one of Black Speech. The Black Speech is 63% consonants compared to the Elvish samples' 52% and 55%. In aggressive speech consonants become longer and vowels shorter so Black Speech sounds harsher while containing far more voiced plosives making the sound of the language more violent.