Definition of "sonorously"

Now old Falkenmeyer's fiddle feelingly quavered a few notes, then sonorously heralded the preliminary bass of the first set. Daddy Stein, standing in the middle of the room, clapped his hands for attention.

1907, Barbara Baynton, edited by Sally Krimmer and Alan Lawson, Human Toll (Portable Australian Authors: Barbara Baynton), St Lucia: University of Queensland Press, published 1980, page 241

Cox’s thing is defending flimsy cases, and as he strode round the platform declaiming sonorously, like Rumpole on a particularly outrageous brief, it was easy to see why they pay him so well.

2018, Anne Perkins, “A Dad’s Army-style Brexit looms. ‘Don’t panic!’”, in Guardian‎