Tympanic membranes allow grasshoppers and their relatives to detect the mating calls of other grasshoppers. Grasshoppers use their tympanic membranes to perceive airborne sounds from their environment, similar to the human sense of hearing. Additionally, these membranes allow grasshoppers to perceive sounds made by approaching predators, according to the University of California, Riverside.
Grasshoppers produce noises in a process called stridulation. This entails rubbing a rough patch of their leg, called a scraper, across the forewing. They make these sounds for territorial and breeding purposes. It is very important for grasshoppers to hear the sounds made by other grasshoppers, so they have evolved very large tympanic membranes to detect the sound waves.
According to the American Association for the Advancement of Science, in humans, these airborne sound waves are converted into waves carried by a fluid via several small bones. These delicate bones connect to the tympanic membrane on one side and the cochlea on the other. This is important because the sensory cells that line the cochlea must stay wet. Until recently, scientists were unable to understand how insect hearing worked, as they could not find any analogous structures in insects.
Using x-rays, scientists recently discovered structures in katydids that perform a similar function. Because katydids are very close relatives of grasshoppers, it is likely that they possess similar structures as well. However, confirmation may take some time; due to their extremely small size, these structures are hard to find during a dissection.