Sound navigation and ranging

Symptoms resulting from exposure to infrasound can include fatigue, headache, nausea, concentration difficul ties, disorientation, seasickness, digestive disorders, cough, vision problems and dizziness .”

One study has suggested that infrasound may cause feelings of awe or fear in humans . It has also been suggested that since it is not consciously perceived, it may make people feel vaguely that odd or supernatural events are taking place.

The majority of the sound from volcanoes is low frequency (below 20 Hz, the threshold of human hearing) and is termed infrasound. Recent research has demonstrated how infrasound can be used to detect, locate, characterize, and quantify volcanic eruptions , providing a valuable tool for volcano monitoring.

There is no agreement about the biological activity of infrasound. Reported effects include those on the inner ear, vertigo, imbalance, etc.; intolerable sensations, incapacitation, disorientation, nausea, vomiting, and bowel spasm; and resonances in inner organs, such as the heart.