ACOUSTIC NOISE INCREASES A LITTLE AFTER THE MOST ACTIVE AURORAE
Read the latest publication [5]: BNAM2004, Mariehamn, Åland (pdf-file, 1.2 Mb).
-> The paper describes the very first, preliminary attempt to record and analyze aurora related sounds related to the April 6-7 2000 event.
-> More details of this pilot material will be published later. The work with high quality acoustical measurements made during other active aurorae continues.
(News published only on this page 12.11.2001)
Two audio recordings: 6.-7.4.2000 and 11.-12.4.2001, contain sound material which can be related to (correlated with) other physical measurements of those geomagnetic storms. There are also other recordings made during active aurorae (2000-2001) which contain similar exceptional sound material. The recorded sounds and effects, auroral sounds, as we believe, are not present in the reference recordings made with the same instruments at the same places during nights with normal geomagnetic activity.
The recordings have been made with professional instruments of highest quality. There is no possibility that, e.g., the microphone has directly picked up effects of geomagnetic or electrical fields. These fields have been measured simultaneously separately. Many audio professionals in our unit have heard the recordings and agree that these are real sounds with many natural acoustic features, like echoes, sounds which are somehow created by the nature, not by any technical failure.
The recordings contain almost all auroral sound types described
earlier
by observers around the world.
Up to now, three persons who have earlier heard auroral crackling have
listened to the recordings and recognized the sounds similar to those
they
heard.
More details will be published later!