Empty Barrels Make the Most Noise

Did you ever notice that people who have the most to say often have the least to contribute? 

This expression is a reminder that those who are full from knowledge because they take the time to listen, usually make the greatest and most significant contributions in a quiet and confident manner. 

Those that talk incessantly are usually looking for a spotlight to perform under rather than an opportunity to learn and grow.  Therefore, their conversation becomes noise, just like empty barrels when they are jostled.