The crow of a rooster is almost impossible to mistake, not only for its distinctive structure but also for its impressive volume. Recent measurements have recorded peaks of 140 decibels, a noise level comparable to a fighter jet taking off. That raises an obvious question: how do roosters avoid going deaf from their own repeated crows?
A team of Belgian researchers set out to answer that question. By analyzing the skulls of several roosters with computed tomography, they discovered that roosters can temporarily close their ear canal when they open their beak to crow.
To measure the actual noise level, the researchers equipped three roosters with microphones. Their crows lasted between 1 and 2 seconds, with two recordings exceeding 130 decibels and a third reaching 143 decibels — something like standing in the middle of an active aircraft carrier.
The CT scans revealed the protective mechanism: when a rooster opens its beak, it can close up to 25 percent of its ear canal, while soft tissue moves to cover 50 percent of its eardrum, significantly dampening the impact on its ears.
Hens are a different story. Their ear canals narrow but do not close, and their own calls do not exceed 70 decibels. They also don't go deaf from the rooster's crow, because the damaging effect diminishes greatly with distance, and there is another advantage: birds have the ability to regenerate their hair cells, something that, for now, mammals cannot do.
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