A joyous stir was now audible in the hall: gentlemen’s deep tones and ladies’ silvery accents blent harmoniously together, and distinguishable above all, though not loud, was the sonorous voice of the master of Thornfield Hall, welcoming his fair and gallant guests under its roof.
There are no more uses of "sonorous" in the book.
Show samples from other sources
The candidate discussed weighty matters in rich, sonorous tones.
I prefer traditional sonorous chords to the dissonant chords with which she likes to experiment.