List of unexplained sounds

All of the NOAA sound files in this article have been sped up by at least a factor of 16 to increase intelligibility by condensing them and raising the frequency from infrasound to a more audible and reproducible range.

According to NOAA, the Whistle is similar to volcanogenic sounds previously recorded in the Mariana volcanic arc of the Pacific Ocean.

[2] Bloop is the name given to an ultra-low-frequency and extremely powerful underwater sound detected by the U.S. National Oceanic and Atmospheric Administration (NOAA) in 1997.

[3] According to the NOAA description, it "rises rapidly in frequency over about one minute and was of sufficient amplitude to be heard on multiple sensors, at a range of over 5,000 km (3,100 mi)."

While the audio profile of Bloop does resemble that of a living creature,[4] the source was a mystery both because it was different from known sounds and because it was several times louder than the loudest recorded animal, the blue whale.

Numerous icequakes share similar spectrograms with Bloop, as well as the amplitude necessary to spot them despite ranges exceeding 5,000 km (3,100 mi).

It was loud enough to be heard over the entire Equatorial Pacific Ocean autonomous hydrophone array, with a duration of about 2 minutes and 43 seconds.

Due to the uncertainty of the arrival azimuth, the point of origin could only be narrowed to between Bransfield Straits and Cape Adare.