If you've heard a chorus of crickets, you know that orthopterans make sound. Males make nearly all the sounds, to defend territories and attract females. Specialized body parts are rubbed together (stridulation) to produce the sound. Male grasshoppers, for example, rub hard edges (scrapers) of their hind legs against rows of tooth-like bumps (files) on their front wings. Male crickets chafe their front wings together, also causing files to rub scrapers. Females detect the sounds with ears on their front legs or their abdomens. Like car speakers that blast loud music, natural amplifiers have evolved as orthopteran males try to outcompete each other. The amplifier may be a body part, such as a shield-like plate that reflects sound (in katydids), or a part of the environment, such as a burrow used by singing crickets. Older males are at a disadvantage, at least in some species, because their worn-down files do not make as loud a sound.

An insect has a brain, connected to bundles of nerves (ganglia) in each of its three body segments. Like us, they have sensory nerves that receive information from their environment and send it to the brain. Information comes from many types of touch receptors. Touch-sensitive hairs all over an insect's body are sensitive enough to detect vibrations in the air, such as from an approaching predator. Insect hairs also do chemical detection (chemoreception). Pores at the end of chemoreceptors on mouthparts or other body parts allow odors to reach the nervous system. Insect antennae may have thousands of chemoreceptors, used to detect chemicals in the air (pheromones) emitted by members of the opposite sex. An insect, like us, has a pair of eyes on its head. But, insect eyes are compound, with hundreds or thousands of lenses, together making an image consisting of spots of light, like pixels. An insect's sound receptors are on its legs.