Boolean: Whistlers AND Birdsong (474), whistlers AND VLF (6960), whistlers AND ELF (3640), ionosphere AND birdsong (23), ionosphere AND whistlers (6050), ionosphere AND chirps (1430),
Terms: auroral chorus (750), dawn chorus (151000),
Boolean: "dawn chorus" AND (ELF OR VLF) (2010), "dawn chorus" AND ionosphere (542), "dawn chorus" AND magnetosphere (642),
Terms: souffleurs (829), birdsong (1330000), chippers (840000), trillers (8760), mimics (3920000),
Terms: whistlers (233000), radioacoustic (578), photoacoustic (106000), natural radio emissions (3400), natural radio (34100), magnetospheric emissions (35), sferics (30500), VLF receiver (7340), whistler listening (17), sunrise whistlers (5),
Terms: insect wing sounds (6),
European Space Agency - Sounds from Space
Terms: atmospheric whistler (6), infrasound (214000), atmospheric infrasound (618), infrasonic (122000), near infrasonic (46), geomagnetic activity (172000), ocean sounds (103000), microbaroms (146), seismic waves (373000), radio acoustic sounding (5470), geomagnetic pulsations (4350), thunderstorms (18300000), acoustic energy (473000), hydroacoustics (50000),
Terms: ionospheric physics (11600), audio-frequency radio waves (20), ion-cyclotron resonance (67400), electron-cyclotron resonance (72300),
Professor Millett Morgan, Radio Physics Expert, Dies at 87
Tutorial - The Magnetosphere - C.T. Russel (UCLA) - The source turned out to be other electromagnetic waves, not generated in the atmosphere but generated by the particles themselves. These waves had been detected by receivers on the ground for many years. One of the types of emissions was called the dawn chorus, which sounded much like the chirping of birds.
NASA online VLF receiver at SpaceWeather.com + Real Time VLF
Antarctica Dec 29 1999 + VLF sounds
Wikipedia - Dawn chorus (electromagnetic)
S. P. McGreevy's ground-based ELF-VLF recordings - 1991-1998 + 1996-2005 + New-Mexico/California
NASA - McGreevy ground-based VLF recordings
NASA - Earth Songs + Inspire
NOAA - Infrasonic and Near Infrasonic Atmospheric Sounding and Imaging
NOAA - Low-Frequency Atmospheric Acoustic Energy Associated with Vortices Produced by Thunderstorms
Infrasound by John D. Cody
Infrasonic Symphony: Science News Online, Jan. 10, 2004