"Nothing reveals a person's character so much as their voice." This quote from the British writer and Prime Minister Benjamin Disraeli highlights the importance of emotional language, which is expressed mainly through the tone of voice.
In the Public Relations (PR) industry, we accept the 7-38-55 rule. These numbers stand for to the results obtained in the 1960s by psychologist Albert Mehrabian, a specialist in non-verbal communication: only 7% of the information comes from what is said, 38% from how it is said and 55% from what the body says.