article_snippet.sent: We may not be able to hear it, but Earth Earth is constantly oscillating and creating a hum that has been likened to the ring of a bell.
article_snippet.sent: it's long been known that earthquakes and a hum that has been likened to the ring of a bell seismic activity contribute to this ringing, but researchers have now proved ocean waves also play a role.
article_snippet.sent: As so-called short waves collide near the surface they create weak microseismic waves, which combine with long, more powerful waves dragging across the ocean's floor to create the constant hum.
article_snippet.sent: It's long been known that earthquakes contribute to making the Earth ring like a bell, but researchers have now proved ocean waves also play a role.
article_snippet.sent: As  short waves collide near the surface they create weak microseismic waves, which combine with long waves on the ocean's floor to create a constant hum .
article_snippet.sent: This oscillation is caused by vibrations and researchers in the mid-1980s found the hum can drop as low as an E flat, 20 octaves below middle C on the musical scale.
article_snippet.sent: This oscillation is caused by vibrations and researchers in the mid-1980s found that the hum can drop as low as an E flat, 20 octaves below middle C on the musical scale.
article_snippet.sent: A team of Japanese and Californian seismologists first suggested ocean waves may cause this hum in 2004.
article_snippet.sent: A team of Japanese and Californian seismologists first suggested ocean waves may cause this constant hum in 2004.
article_snippet.sent: the hum is the least understood part of Earth's oscillations.'
article_snippet.sent: This means that earthquakes, colliding oceans and long waves all combine to create Earth's hum .
article_snippet.sent: This means that all three theories - earthquakes, colliding oceans and long waves - combine to create the Earth's hum. 
article_snippet.sent: Now we know where this ringing comes from and the next question is: what can we do with this ringing,' Mr Ardhuin told the American Geophysical Union (AGU).
highlights_snippet.sent: It has long been known that Earth is constantly oscillating and 'humming'
  
highlights_snippet.sent: Earthquakes cause a certain level of hum, but a study claims different sized ocean waves also contribute to Earth's oscillations .
  
highlights_snippet.sent: As water collides, a study creates weak microseismic waves that cause a hum .
  