I'm surprised no one has mentioned it but jogging/walking/biking/driving with headphones in/on is more dangerous than silent airplanes. Now that its getting nice out we are starting to see that already, trying to ride a bike down the multipurpose trail and someone is walking along with headphones on and doesn't hear you coming or your "on the left" call and steps in front of you or swings their arms. Having the headphones on you loose the situational awareness and don't hear anything else coming be it an airplane with no engine or a stray dog or car or bicycle or mugger or etc.