The tone of Dracula is unique, given that it is an epistolary novel: there is no one omniscient narrator to tie the story together. Rather, there are multiple first-person narrators, all speaking in their own voices. Stoker's authorial tone is therefore somewhat obscured within the text by his choice of epistolary style: individual characters have their own biases, and speak in distinct voices, though all are written by Stoker.
Nonetheless, one can still identify authorial tone in Dracula by examining the unilateral assumptions and language choices made by all characters. For example, each protagonist believes completely and utterly in the divine power of God and the Christian religion. Despite their terror and fear, Mina Harker, Jonathan Harker, Van Helsing, Quincey Morris, Dr. Seward, and Arthur are united in their faith. This has less to do with individual characterization and more to do with tone, conveying Stoker's own personal attitudes regarding religion's importance in the face of otherworldly danger.
Furthermore, each of the male characters (including Dracula) adopts an infantilizing tone when addressing or discussing Lucy and Mina, the main female protagonists. These women are portrayed as pure, innocent, and childlike, whether for the purposes of glorification or implied future defilement. This universal tone is evident at the end of Chapter 16, when Dr. Seward and the other male protagonists destroy the vampire within Lucy:
There in the coffin lay no longer the foul Thing that we had so dreaded and grown to hate that the work of her destruction was yielded as a privilege to the one best entitled to it, but Lucy as we had seen her in life, with her face of unequaled sweetness and purity.
Lucy becomes an object rather than a person in this passage: her humanity is defined by her "purity," for after she has been defiled by a supernatural "other," she is no longer Lucy but a "Thing." This fear of female impurity runs deep in Dracula, expressed by more than one character and legitimized by the ethically righteous protagonists. Though each protagonist narrates their own passages with a distinct voice, such similarities in tone on certain subjects reveal Stoker's authorial tone in Dracula.