Sound waves are actually very strong. Strong enough to break glasses in fact. Susan the opera singer likes to shatter glasses in her free time by using her voice. She harnesses the idea of resonance to do so. If another object having the same natural frequency is impacted by these sound waves, it may begin to vibrate at this frequency as well. As susan sings, her high pitched tone creates a sound wave that matches the frequency that matches the natural frequency of the glass. Glass resonates or vibrates at the same frequency so energetically that it shatters. When the sound waves strike the glass the phenomena of resonance is illustrated. Resonance occurs when one vibrating object transfers energy to a second object causing it to vibrate. The engr. transfer is most efficient when, compared to the first object, the second object has that same natural frequency.