You Can Hear Your Own Heartbeat: Where the Quietest Places on Earth Are Located## Transcription note: This is a direct translation of the title/heading provided in the original text.

It's almost impossible to identify an absolutely quiet natural place, since the sound level is influenced by many factors - wind, wild animals, vegetation movement, presence of tourists and passing airplanes.

As reported by BAKU.WS, this is according to IFLScience.

Nevertheless, one of the best contenders for the title of the quietest national park in the US is considered to be the Haleakala crater. It is located at an altitude of 3055 meters above the Pacific Ocean, on the East Maui volcano on the Hawaiian island of the same name.

According to the National Park Service, natural sounds, wide panoramas and dark night sky create the unique atmosphere of Haleakala. The background noise level in the crater is so low that it almost reaches the threshold of human hearing.

Interestingly, the deep crater protects the area well from wind, while the arid and almost lifeless landscape without vegetation and animals reduces the number of natural sounds. Therefore, it can indeed be unusually quiet here.

The National Park Service notes in a separate document that the natural sound background is a key resource of the park, since low noise levels play an important role in the state of its ecosystems. In 2003, specialists measured both natural and overall acoustic background. The average daytime level of natural noise varied from 21 decibels in hard-to-reach parts of the park to 45 decibels near the coast. The Haleakala crater is among the quietest zones in national parks - here the sound level can drop to 10 decibels, which is close to the hearing threshold. The average daytime noise similarly fluctuates: from 23 decibels in remote areas to 46 decibels where there are more visitors.

Despite these fluctuations, the silence here is still impressive - some tourists claim they can hear their own heartbeat. However, in a specially built room designed to minimize sound, the background noise level reaches -24.9 decibels.

The quietest place on Earth created by humans

The anechoic chamber at Orfield Laboratories in Minneapolis (Minnesota) is considered the quietest place in the world. It has received this title three times. Orfield Laboratories explains:

"An anechoic chamber is a room that absorbs up to 99.99% of sound. In the NVLAP accredited acoustic laboratory, it can be used both in fully anechoic mode and with the addition of a reflective floor. The approximate dimensions of the structure: 3.8 × 3.2 × 2.1 meters".

After receiving the first accreditation in 1997, the laboratory applied to the Guinness Book of Records to record low noise levels in the chamber (-9.4; -13.4 and -24.9 decibels), which secured three world records in the category "The Quietest Place on Earth" in 2004, 2012 and 2021. Now the chamber is used as a research facility and as a place for tourists interested in sensory deprivation.

The chamber is specially designed to maximize sound absorption. Fiberglass and foam wedges disperse sound energy and prevent the formation of standing waves, and the structure itself stands on vibration absorbers that minimize external vibrations. Many myths have emerged around it, for example, that it's impossible to stay inside for more than 45 minutes. One journalist spent three hours there, disproving these rumors. Nevertheless, visitors often do experience discomfort - nausea, loss of orientation, and can also hear their blood flowing or even their eyes blinking.

Why sound can be "negative"

Although sound itself cannot be negative, the value in decibels can go into minus. The National Institute on Deafness and Other Communication Disorders explains:

"The decibel scale is not linear - it is logarithmic, which better reflects how the human ear perceives loudness. For example, if a building 24.5 meters tall is increased by just 3 meters, it becomes slightly taller - this is a linear change. But increasing sound from 80 to 90 decibels means a tenfold increase in intensity and will be perceived by us approximately as doubling the loudness".

Zero decibels corresponds to the threshold of human hearing. In anechoic chambers, the background can be even lower, which gives "negative" values on measuring instruments.