infrasounds
Below hearing range
Infrasounds are sound waves with frequencies below the range of human hearing—typically under 20 hertz.
Though inaudible, infrasound can be felt as vibration or pressure.
Natural sources include earthquakes, volcanoes, and ocean waves; artificial sources include explosions and industrial machinery.
Some researchers have linked infrasound exposure to feelings of unease or dread.
Occurring seldom or rarely
- hertzFrequency measurement unit
- decibelsAcoustic intensity units
- waveformGraphed oscillation pattern
- resonanceAmplified oscillation at natural frequency
oscillation · amplitude · propagation · attenuation · pressure · threshold · hearing · auditory
Sudden ground movement
- tremorsSlight shaking movements
- seismologyStudy of ground tremors
- tectonicsStudy of crustal deformation
- magnitudeSize or scale
epicenter · seismograph · seismometer · P-waves · S-waves · faults · aftershocks · foreshocks
Aquatic mammals, fully marine
- oceanMassive saltwater body
- songsMusical vocal compositions
- humpbackBaleen whale species
- communicationExchanging ideas or information
migration · deep-sea · pod · marine · long-range · echolocation · vocalization · underwater
Storm's acoustic aftermath
- volcanoesLava-emitting geological formations
- waterfallsVertical river descents
- avalanchesMassive snow collapses
- meteorsLuminous atmospheric debris
wind · storms · aurora · geysers · landslides · atmospheric · weather
Low rolling sound
- herdGrazing animals together
- communicationExchanging ideas or information
- matriarchFemale family leader
- savannaTropical grassland, sparse trees
long-distance · trumpeting · migration · pachyderm · Africa · intelligence · warnings · vibrations
Ongoing observation of something
- arraysOrdered element collections
- meteoritesExtraterrestrial rocks on Earth
- avalanchesMassive snow collapses
- atmosphericOf the air above
surveillance · early-warning · military · sensors · stations · analysis
low-frequency
Occurring seldom or rarely
resonance · oscillation · amplitude · propagation · attenuation · pressure · threshold · hearing · auditory · spectrum
earthquakes
Sudden ground movement
- tremorsSlight shaking movements
- seismologyStudy of ground tremors
- tectonicsStudy of crustal deformation
magnitude · epicenter · seismograph · seismometer · P-waves · S-waves · faults · aftershocks · foreshocks · subduction
cetaceans
Aquatic mammals, fully marine
communication · migration · deep-sea · pod · marine · long-range · echolocation · vocalization · underwater
thunder
Storm's acoustic aftermath
- volcanoesLava-emitting geological formations
- waterfallsVertical river descents
- avalanchesMassive snow collapses
meteors · wind · storms · aurora · geysers · landslides · atmospheric · weather
rumbling
Low rolling sound
- herdGrazing animals together
- communicationExchanging ideas or information
- matriarchFemale family leader
savanna · long-distance · trumpeting · migration · pachyderm · Africa · intelligence · warnings · vibrations
monitoring
Ongoing observation of something
- arraysOrdered element collections
- meteoritesExtraterrestrial rocks on Earth
- avalanchesMassive snow collapses
atmospheric · surveillance · early-warning · military · sensors · stations · analysis
infrasoundsultrasounds
Imaging via high-frequency waves
ultrasonic waves · ultrasound · ultrasonics · high-frequency sound