Tobacco hornworm body hairs may hold clues to cheaper microphones
Experiments in an anechoic chamber suggest caterpillars detect airborne sound through sensitive hairs, although the unpublished findings are not conclusive.
Tobacco hornworm caterpillars may detect airborne sound through tiny body hairs, according to ongoing research reported by WIRED and republished from The Conversation.
Researchers tested the caterpillars in an anechoic chamber over approximately a year, exposing them to controlled platform vibrations and airborne sounds. An accelerometer was used to distinguish sound-induced movement from direct vibrations travelling through the platform.
The caterpillars continued to react to airborne sounds even when platform vibrations fell below the threshold at which they visibly responded to direct vibration. The result provided evidence that the animals were detecting sound through the air rather than solely sensing movement in the platform.
The researchers then removed selected body hairs, either individually under a microscope or more extensively with tweezers. Defensive reactions fell sharply at some sound frequencies, depending on which hairs were removed. The findings suggest the hairs contribute to sound detection, but do not establish that they are the caterpillars’ hearing organs.
The work has not yet been published in a peer-reviewed journal. Researchers are continuing to investigate which hairs may respond to particular frequencies and how the mechanism operates.
The biological system could eventually inform cheaper directional microphones. Designs inspired by the hairs might measure air-particle velocity alongside sound pressure, helping identify the direction from which a sound wave originates. That remains a potential application rather than an established technology.
