The perception of sound in association with auroras

Abstract

The aurora is a large-scale, dynamic optical phenomenon occurring at 80–100-km altitude and high geomagnetic latitude, caused by energetic electrons precipitating into the upper atmosphere. No sound waves in the audiofrequency domain can propagate from auroral altitudes to the ground, and none have ever been physically detected. Yet there are numerous reports of auroral “sounds” perceived during auroral displays [see review by S. M. Silverman and T. F. Tuan in Adv. Geophys. 16 (1973)]. While some reports may have an obvious explanation related to environmental sounds, we propose that auditory sensations during auroral displays are the result of an illusory associative recall, or the consequence of a synaesthetic effect: when a large portion of the retina is stimulated with coherently moving patterns (as in the aurora), auditory associations may be triggered by optical-acoustic channel interaction, perhaps at the superior colliculus level. This interaction may be enhanced during particular behavioral states, such as usually prevailing during the observation of aurora (darkness, cold, silence, isolation).