Cicadas are fascinating insects known for their presence during warmer months, primarily due to the loud sounds they produce. These creatures, often emerging in large numbers, create a natural soundtrack that can dominate outdoor environments. Their acoustic abilities set them apart, prompting curiosity about how such small beings generate noise. Exploring the science behind their sounds reveals biological processes and behaviors that contribute to their acoustic output.
Cicada Sound Levels
Cicadas are among the loudest insects globally, with their calls reaching impressive decibel levels. Individual cicada calls can range from approximately 70 to 80 decibels when measured at a distance. When many male cicadas congregate, their collective chorus can be significantly louder, sometimes reaching up to 100 decibels or more. For context, 70-80 decibels is comparable to the sound of a vacuum cleaner, while 100 decibels is similar to a lawnmower, a motorcycle, or even a chainsaw.
Some of the loudest species, like the African cicada Brevisana brevis, have been recorded at 106.7 decibels at a distance of 50 centimeters. In North America, certain species can produce calls reaching around 100 decibels or more. The sustained noise level of a combined cicada chorus has been measured at approximately 88.5 decibels, fluctuating between 82 and 89 decibels. This level surpasses federal traffic noise thresholds for residential areas, which are around 67 decibels.
How Cicadas Produce Sound
Male cicadas generate sounds using specialized organs called tymbals, located on the sides of their abdominal base. Each tymbal is a ribbed membrane connected to powerful muscles.
When these muscles contract, the tymbal membrane rapidly buckles inward, producing a clicking sound. The tymbal springs back when the muscle relaxes, and this process can occur at an astonishing rate, ranging from 120 to 480 times per second. The rapid succession of these clicks creates the continuous buzzing or whirring sound. The cicada’s hollow abdominal cavity acts as a resonating chamber, amplifying the sound produced by the tymbals.
The Purpose of Cicada Calls
Male cicadas produce loud sounds for communication, primarily to attract mates. Each cicada species possesses a distinct call, which helps females identify and locate males of their own species for reproduction. This specificity ensures successful mating within the same species.
Male cicadas often gather in large groups, forming “choruses” where they synchronize their calls. This collective calling amplifies the sound, making it easier to attract females from greater distances. Beyond mating, cicadas also use sounds for other purposes, such as producing a disturbance squawk when threatened or captured, and calls may deter predators.
Experiencing Cicada Sounds
The experience of living with loud cicada sounds varies for people, ranging from a seasonal novelty to a potential nuisance. During large periodical cicada emergences, the volume of their calls can be considerable, leading to concerns about noise exposure. While cicada noise levels can reach 100 decibels, the threshold where prolonged exposure can begin to cause hearing damage, short exposures are unlikely to cause permanent hearing loss.
If the sounds are loud or prolonged, such as when standing very close to a dense chorus, wearing earplugs or noise-canceling headphones can be a reasonable precaution. For individuals with tinnitus, the continuous buzzing can be more bothersome. Limiting exposure by staying indoors during peak activity times or using hearing protection is recommended. Periodical cicada emergences, while intense, are temporary events, typically lasting only a few weeks.