The sound of the blue whale, which measures 188 decibels and travels up to 500 miles, is the loudest among all animals, according to the Smithsonian National Zoological Park. On land, the loudest animal sound comes from the howler monkey and can be heard for up to 3 miles.
Scientists also measure the sounds that animals make relative to their size. Using this ratio, the loudest animal sound is produced by an insect called the water boatman. This tiny bug measures in at less than 0.08 inches, but it emits a singing sound that can measure as high as 99.2 decibels. Its average noise level is 78.9 decibels.