During their church choir's annual picnic, Joe and Susan wandered off to explore the surrounding woods. But when they decided to return to the picnic site, they discovered that they couldn't find their way back. They hadn't wandered very far. They were almost sure that they were still within hearing distance of the rest of the group. Which one of them should shout for help? Susan, who was a physicist as well as a soprano in the choir, told Joe that he should shout and she would rest her vocal cords for her next solo. Besides, she explained, Joe's deep bass voice would carry farther because it would send out sound waves with longer wavelengths. Her higher frequency voice, on the other hand, would send out sound waves of shorter wavelengths that wouldn’t carry as far. That's because a sound wave travels only a certain number of wavelengths before it stops. It's as if a person with short legs and a person with long legs were walking at the same speed. The short legged person will take smaller steps but more frequent ones, while the long legged person will take longer, less frequent steps. If both get tired and stop after taking 1,000 steps, the long legged person will have traveled farther.