The sound of nails on a chalkboard or screams may send shivers down the spine for a good reason. A new study shows annoying sounds trigger a highly emotional response in the brain. Researchers found the part of the brain that regulates emotions, the amygdala, appears to take over the hearing part of the brain when people hear an extremely annoying sound. This application includes 45 of the most annoying ringtones and sounds known to man. Some are included just for fun, while others are scien