О РЕГИСТРАЦИИ ШУМОВ, СОЗДАВАЕМЫХ ЛАСТАМИ НА МЕЛКОВОДЬЕ

Особенности шумов ласт легководолазов, свидетельствующие о мультипольном характере излучения их источников, предсказаны теоретически. Экспериментально продемонстрирована перспективность обнаружения низкочастотных составляющих шума ласт водолазааквалангиста с помощью приемника градиента давления. Полученные результаты свидетельствуют о том, что низкочастотные шумы ласт легководолазов могут быть успешно использованы для пассивного обнаружения и мониторинга как в интересах обеспечения безопасности рекреационного дайвинга, так и в антитеррористических целях. Ключевые слова: легководолаз, шумы, ласты, обнаружение, приемник градиента давления.The features of noises of fins of scuba divers, indicating the multipole nature of emission, were predicted theoretically. Advantages of detecting the low frequency components of the noises of fins of opencircuit scuba diver with the pressure gradient receiver were experimentally demonstrated. The results indicate that the lowfrequency noises of fins can be successfully used for passive detection and monitoring, both in the interests of ensuring the safety of recreational diving and for antiterrorism aims. Keywords: scuba diver, noises, fins, detection, pressure gradient receiver.

О РЕГИСТРАЦИИ ШУМОВ, СОЗДАВАЕМЫХ ЛАСТАМИ НА МЕЛКОВОДЬЕ

Особенности шумов ласт легководолазов, свидетельствующие о мультипольном характере излучения их источников, предсказаны теоретически. Экспериментально продемонстрирована перспективность обнаружения низкочастотных составляющих шума ласт водолазааквалангиста с помощью приемника градиента давления. Полученные результаты свидетельствуют о том, что низкочастотные шумы ласт легководолазов могут быть успешно использованы для пассивного обнаружения и мониторинга как в интересах обеспечения безопасности рекреационного дайвинга, так и в антитеррористических целях.frequency components of the noises of fins of opencircuit scuba diver with the pressure gradient receiver were experimentally demonstrated. The results indicate that the lowfrequency noises of fins can be successfully used for passive detection and monitoring, both in the interests of ensuring the safety of recreational diving and for antiterrorism aims.

Evolution of directional hearing in moths via conversion of bat detection devices to asymmetric pressure gradient receivers

Small animals typically localize sound sources by means of complex internal connections and baffles that effectively increase time or intensity differences between the two ears. However, some miniature acoustic species achieve directional hearing without such devices, indicating that other mechanisms have evolved. Using 3D laser vibrometry to measure tympanum deflection, we show that female lesser waxmoths (Achroia grisella) can orient toward the 100-kHz male song, because each ear functions independently as an asymmetric pressure gradient receiver that responds sharply to high-frequency sound arriving from an azimuth angle 30° contralateral to the animal's midline. We found that females presented with a song stimulus while running on a locomotion compensation sphere follow a trajectory 20°–40° to the left or right of the stimulus heading but not directly toward it, movement consistent with the tympanum deflections and suggestive of a monaural mechanism of auditory tracking. Moreover, females losing their track typically regain it by auditory scanning—sudden, wide deviations in their heading—and females initially facing away from the stimulus quickly change their general heading toward it, orientation indicating superior ability to resolve the front–rear ambiguity in source location. X-ray computer-aided tomography (CT) scans of the moths did not reveal any internal coupling between the two ears, confirming that an acoustic insect can localize a sound source based solely on the distinct features of each ear.