Apparently teenagers have discovered a ring tone that adults can't hear. This is true. The ringtone has a very high pitch. As people reach adulthood, they start to develop aging ear, which is the inability to hear high-frequency sounds. So with this super new ringtone, students can receive text messages without the teacher being able to hear. It's also funny that the tone was initially developed to keep teenagers away from certain stores because store owners thought they'd find the sound irritating. I guess it's worth putting up with the noise if it means knowing whether Sally will meet you at your locker after B period. Check out the article.