Like anyone with rowdy neighbors, oysters may be feeling stressed thanks to the growing problem of underwater noise pollution, and are trying to filter out the racket.

New research published Wednesday in PLoS One reveals that oysters will close their shells when exposed to noises along a range of frequencies that includes the sounds emitted by known noise polluters like cargo ships and underwater oil exploration.

In oysters, closed shells are an indicator of distress. Under optimal conditions, bivalve mollusks will keep their shells open, and are thought to shut them only when feeling stressed or threatened. Clamping their shells to screen out noise pollution or other artificial irritants could prevent oysters from perceiving important biological cues, said the authors of the study.

Oysters “must be able to hear breaking waves and water currents,” which could trigger their biological rhythms, said Jean-Charles Massabuau, research director at the French National Center for Scientific Research and an author of the study. “To hear the current arriving could prepare them for eating and digesting, possibly as when we hear and smell that somebody is preparing dinner.”