Cicadas are one of the most recognizable insects. These insects spend the majority of their lives underground as nymphs, emerging only for a short adult phase focused on reproduction. The loud, buzzing sound that defines their presence is exclusively produced by males and serves a specific biological function. The volume they achieve is remarkable for an insect.
Quantifying the Noise: Decibel Levels and Real-World Comparison
While a single cicada produces high decibel sounds, the true volume occurs when they gather in large numbers. The collective sound of a cicada chorus often measures between 82 and 89 decibels, comparable to a loud highway or heavy city traffic. Since 85 decibels is the threshold where hearing protection is recommended, this sustained noise level can be hazardous.
At close range, the sound from a group of males can easily exceed 100 decibels, a volume similar to a passing motorcycle or factory machinery. The current record holder for the loudest insect is the African species Brevisana brevis, measured at 107 decibels from a distance of 20 inches, which is about as loud as a chainsaw.
The Anatomy of Cicada Sound Production
The immense volume produced by the male cicada results from a specialized anatomical structure called the tymbal. This corrugated, drum-like membrane is located on the sides of the insect’s abdomen. Sound is generated by the rapid flexing of this membrane, unlike the rubbing motion used by crickets.
Powerful muscles attached to the tymbal rapidly pull it inward, causing the membrane to buckle and produce a sharp click. When the muscle relaxes, the tymbal springs back to its original position, creating a second click. This action can be repeated at an extremely high frequency, sometimes buckling the membrane 120 to 480 times per second, which registers as a continuous sound.
The sound created by the tymbal is then amplified by the cicada’s hollow abdomen. This abdominal cavity contains enlarged air sacs that function as a resonance chamber. The chamber is tuned to the frequency of the tymbal’s clicks, allowing the small initial sound to be radiated into the environment with astonishing volume.
The Biological Purpose of Loudness
The primary reason for the cicada’s extreme volume is to facilitate reproduction. The loud, species-specific mating call is designed to attract receptive females from long distances. Males congregate in “choruses,” where they synchronize their calls to create an overwhelming wave of sound.
This collective volume creates a “chorus effect” that attracts females and increases the overall chances of successful mating for the entire group. Males also have quieter courtship songs used when a female is close by, as well as a distinct distress call emitted when they are seized or attacked. The volume produced by large choruses also acts as a defense mechanism, potentially overwhelming the hearing of small predators.