"tones of the voice have much to do in affecting the hearts of those that hear. 2T 615.1"
"A man hath joy by the answer of his mouth: and a word spoken in due season, how good is it!"
Both passages discuss the importance of the tone of voice in communication and its effect on the listener. Proverbs speaks of the joy brought by a well-timed word, while EGW emphasizes the impact of vocal tones on the hearts of hearers.
"Many who might be useful men are using up their vital force and destroying their lungs and vocal organs by their manner of speaking. Some ministers have acquired a habit of hurriedly rattling off what they have to say as though they had a lesson to repeat and were hastening through it as fast as possible. This is not the best manner of speaking. By using proper care, every minister can educate himself to speak distinctly and impressively, not to hurriedly crowd the words together without taking time to breathe. He should speak in a moderate manner, that the people may get the ideas fixed in their minds as he passes along. But when the matter is rushed through so rapidly, the people cannot get the points in their minds, and they do not have time to receive the impression that it is important for them to have; nor is there time for the truth to affect them as it otherwise would. 2T 615.2"
"So likewise ye, except ye utter by the tongue words easy to be understood, how shall it be known what is spoken? for ye shall speak into the air."
Both passages address the importance of clear and understandable speech. 1 Corinthians 14:9 directly states the need for easily understood words, while EGW elaborates on how rapid and indistinct speech hinders comprehension and impact.