Pitch is an attribute of sound that can be described as high or low.  Someone who is nervous or frightened may speak in a high-pitched voice as her or his throat tightens.  Listeners may be less likely to believe your message if you speak in a high-pitched voice.

People who speak in a low-pitched voice project calmness and control.  Listeners are more likely to have confidence in a speaker using a low-pitched voice.  If you are nervous or tense as you prepare to speak at a meeting or with a client, make a conscious effort to relax your body.  Drinking something warm will help relax your vocal cords so you can speak in a low-pitched voice.