Click on a date in the calendar above to listen to an archived recording of the previous one week (168 hours) of Earth sound. The average (rms) energy recorded each day is represented by the color scale ; the brighter the color, the greater the energy. Audio volumes have been normalized: in recordings containing low energy (dark colors) the audio volume is increased to highlight the Earth's natural background ambience; during energetic periods (bright colors) the volume is reduced to accommodate the powerful signals from large events. Audio is unavailable on days marked ×.