We have all had that moment in school where a student's phone starts ringing in class. It keeps going for a while but the teacher keeps lecturing. How is that not distracting to the lecturer? Well, it is because the teacher can not even hear it. It is a new ringtone called TeenBuzz. It is so high pitched that people over the age of 30 can not hear it. However, the younger students in the class have no problem hearing the super irritating and high pitched noise.
This is due to presbycusis, a normal loss of acute hearing that occurs with advanced age. Presbycusis is primarily caused by aging but smoking, ototoxic drugs, noise trauma, diabetes, and a few others causes can worsen the effects as well. Due to the consequences of presbycusis, he or she slowly loses the ability to hear very high pitched noises such as the TeenBuzz ringtone. The ringtone takes advantage of presbycusis as teachers are almost always over the age of 30 so they have no idea that someone's phone is ringing while the other students are extremely annoyed. Next time someone has the TeenBuzz ringtone, you will know how it is possible that young students can hear it, while the older professors fail to hear it.
See which level of frequency you can hear here: