01 · Distance
A natural acoustic duct runs through the ocean a thousand metres down.
The United States Navy found it in 1944.
Whales had been using it for millions of years.
Sped up ten times. At real speed you would hear nothing: it sits below your threshold of hearing.
1.600 km
How far a blue whale’s voice travels through that channel.
Since shipping began, the background noise in that same band — between 20 and 200 hertz — has risen by 32 decibels.
In the Antarctic, the range of their communication has fallen to one per cent.
The loudest animal on earth lost its voice because we raised the noise floor on it.
02 · Frequency
A black hole in the Perseus cluster has spent millions of years pushing the gas around it.
That is a pressure wave. That is sound.
57 octaves
Below middle C. A B flat that NASA describes as a million billion times deeper than the limit of human hearing.
Chandra · Fabian et al. · 2003
03 · Time
Under a hill in Scotland there are fuel tanks cut into solid rock in 1941. Walls forty-five centimetres thick. No doors.
Trevor Cox crawled in through an oil pipe, fired a blank pistol and measured how long it took to fade.
112 s
At 125 hertz. Broadband it was 75 seconds, and that is the figure Guinness certified.
The number depends on the band you measure it in. Always.
04 · Silence
The quietest place on earth was measured in an anechoic chamber in Minneapolis.
People who go in describe hearing their own blood. Nobody lasts long.
Past a certain point there is nothing left to absorb: the noise that remains is made by air molecules colliding with each other.
−24,9 dBA
Silence has a floor too, and it is physical.
Orfield Laboratories · 19 de noviembre de 2021
−5,2 dB
What you get back by slowing a ship down.
Distance, frequency, time and silence.
The four quantities we work with, at their extreme.