Slow Down is a sound recorded on May 19, 1997, in the Equatorial Pacific Ocean

Pacific Ocean

The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...

 by the U.S.

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 National Oceanic and Atmospheric Administration

National Oceanic and Atmospheric Administration

The National Oceanic and Atmospheric Administration , pronounced , like "noah", is a scientific agency within the United States Department of Commerce focused on the conditions of the oceans and the atmosphere...

. The source of the sound remains unknown.

Analysis

The name was given because the sound slowly decreases in frequency

Frequency

Frequency is the number of occurrences of a repeating event per unit time. It is also referred to as temporal frequency.The period is the duration of one cycle in a repeating event, so the period is the reciprocal of the frequency...

over about 7 minutes. The sound was detected at 15°S 115°W. It was recorded using an autonomous hydrophone array. The sound has been picked up several times each year since 1997. One of the hypotheses on the origin of the sound is moving ice in Antarctica. Sound spectrograms of friction closely resemble the spectrogram of the Slow Down. This suggests the source of the sound could be a friction phenomenon of ice rubbing over land.