The tone of your voice, kindly or harsh, is just as powerful as your message.
That is because people read intent from your tone of voice. It sends a direct message about your opinion of them as human beings.
We are hardwired into taking the tone of voice personally.
If your tone does not match your words, people will be confused and perhaps distrustful. You can end up with a misunderstanding, a fight, or a lack of cooperation.
Try to communicate in a pleasant and reasonable manner.
But if you accidentally speak harshly because you are rushed or stressed, explain yourself.
It will decrease the chance of the other person taking offence.
[From 52 Secrets of Psychology– see home page of www.drchrisday.com]