Fun facts about hearing

1. Ears are completely individual just like fingerprints! Yahoo has even explored technology that could unlock a cell phone when held to the ear. 
2. Your cochlea has 16,000 microscopic hair cells called sterocilia.
3. The unit used to measure loudness – the decibel - was named after Alexander Graham Bell, the inventor of the telephone.
4. Why do we turn the radio up when we drive on a highway, and down when we are on side streets? Because those with normal hearing need sound levels to be nearly 10 decibels louder than background noise. This is referred to as the signal-to-noise ratio.

Fun facts source.