The natural world is full of sounds, but the volume achieved by some insects can be astonishing. Despite their miniature size, many insects rely on powerful acoustic signals to survive and reproduce. Sound is a primary channel of communication for these organisms, especially in environments where visual cues are obscured. The noise level generated by some species demonstrates an impressive feat of biological engineering and a necessary adaptation.
Identifying the Loudest Insect
The title of the world’s loudest insect belongs to the African cicada, Brevisana brevis, found in the warmer climates of sub-Saharan Africa. This insect produces a calling song that reaches an average sound pressure level of 106.7 decibels when measured from 50 centimeters away. To put this volume into perspective, 106.7 decibels is comparable to the noise produced by a chainsaw or a jackhammer operating at close range. The sound generated by a single male cicada is loud enough to potentially cause temporary hearing discomfort in a human who stands too close. This extreme volume dwarfs the sound production capabilities of most other insect species.
The Mechanics of Sound Generation
The cicada’s remarkable volume is achieved through a specialized biological structure known as the tymbal, a pair of which sits on the first segment of the insect’s abdomen. The tymbal is a ribbed, drum-like membrane connected to a powerful internal tymbal muscle. When the male cicada wants to “sing,” it rapidly contracts this muscle, causing the membrane to buckle inwards and produce a distinct clicking sound.
As the muscle relaxes, the elastic tymbal membrane springs back, creating a second click. This rapid action of contracting and relaxing the tymbal muscle happens at an astonishing rate, sometimes between 120 and 480 times every second. These individual clicks blur together into the continuous, high-pitched buzzing or whining sound characteristic of the cicada’s chorus. The structure works much like repeatedly popping the metal lid of a jar.
The abdomen acts as a sophisticated sound amplifier. Many cicada species have a mostly hollow abdomen containing large air sacs that function as resonant chambers. These chambers efficiently amplify the vibrations produced by the tymbals, much like the body of an acoustic guitar. To prevent self-inflicted hearing damage, the male cicada possesses a mechanism that temporarily retracts and creases its own eardrums, or tympana, while singing.
Why Insects Need to Be So Loud
The extraordinary volume of the cicada’s call serves several survival purposes. The primary function is reproductive: male cicadas use the noise as a long-distance mating call to attract females of their species. The power of the sound ensures the signal travels far through dense vegetation and over ambient noise, reaching potential mates across a wide area. Females are highly attuned to the specific frequency and rhythm of their species’ song, allowing them to locate a suitable mate even within a massive chorus.
The loud chorus is also a defensive strategy against predators, such as birds and bats. When large numbers of males sing together, the total volume can become overwhelming, disorienting a predator and temporarily hindering hunting efforts. The synchronous singing provides safety in numbers, as the collective noise reduces the chance that any single individual will be targeted. The loud calls are a necessary adaptation for species recognition and a form of acoustic camouflage.