Noise - Anything that interfers with a listener's ability to receive a message.
A telephone ringing may distract
Internal noise is noise within yourself while speaking. Internal noise can be controlled however. Ever heard that little voice inside your head telling you that something is good or bad, or what or what not to do? That is an example of internal noise.
External noise on the other hand can not always be controlled. External noise is the noise in your surroundings by other people and the enviroment. An example of external noise would be giving a speech in class and someone would to sneeze in the middle of your speech messing up your internal thoughts.