Marin Mersenne (1588 -1648)-French theologian, philosopher, mathematician, and music theorist was the first to measure the speed of sound in air, obtaining a result of about 450 m/s, (about 100 m/s higher than the actual speed). The crater Mersenius on the Moon is named after him. ¹⁾

The phonautograph is the oldest known sound recording device, created by Frenchman Édouard de Martinville and patented on March 25, 1857. The sounds recorded by the phonautograph were reconstructed in 2008 using computer techniques. The oldest 20-second recording of a French folk song is from 1860. ²⁾

A 1-decibel increase in noise is actually a 26% increase over the previous state (1 decibel is the smallest change that the average human ear can detect). So, on average, every 3 dB the noise increases twice. ³⁾

The gramophone was created after Emil Berliner made many modifications to Edison's phonograph. For 9 years he improved his product and in 1887 Berliner patented the name gramophone. He experimented with hard rubber ebonite plates until finally, the best raw material turned out to be polyvinyl chloride, which is still used today. ⁴⁾

Crocodiles are the only reptiles to have vocal cords and the only ones capable of roaring loudly. ⁵⁾