Definition of "toneless"

And sure enough she had settled down at once, so that in less than two months it seemed to Stephen that Miss Puddleton must always have been at Morton, must always have been sitting at the large walnut table, must always have been saying in that dry, toneless voice with the Oxford accent: ‘You’ve forgotten something, Stephen,’ […]

1928, Radclyffe Hall, The Well of Loneliness‎, Garden City, NY: Blue Ribbon Books, Book 1, Chapter 7, Section 2, p. 71

The Cumshewa totem poles were dark and colourless, the wood toneless from pouring rain.

1941, Emily Carr, chapter 4, in Klee Wyck‎