February 26, 2024

Humans Hear Much Better Underwater Than Previously Thought – At Times Better Than Seals

That is why it should not be a surprise that a group of experts came to the conclusion that individuals today hear much better on land than under water in a current study. The research study also uses unanticipated info on human hearing.
” In the air, we can figure out the sound instructions within a few degrees, however in water, there is an up to 90 degrees error margin. This is not so unusual, because we are trained to react to the small time distinctions between the ears, which are due to the speed of noise in air. In water, the speed of sound is 4 times higher, and the time differences are much smaller sized,” Jakob Christensen-Dalsgaard explains, concluding, “The outcomes tell us that humans have actually a decreased capability to figure out the direction of noises undersea, therefore confirming that human hearing is not adjusted to work well underwater.”

A graph comparing the hearing of seals, dolphins, and humans underwater. Credit: University of Southern Denmark.
Years of hearing tests
Because the 1950s, several various efforts have actually been made to measure human hearing underwater The US military, for example, has had an interest in comprehending how scuba divers are impacted by undersea surges, and in general, the hearing tests have actually been very different.
Some subjects have been checked with diving devices on, others with neoprene caps, and still others with air-filled diving masks– all of which can affect the test topics hearing.
The authors state that one thing in common with all of these scientific research studies is that they all find hearing thresholds that are greater than the limits we have actually found in their brand-new research study.
Illustration of how the hearing tests were performed. Credit: Jakob Christensen-Dalsgaard, University of Southern Denmark
We hear in addition to seals undersea.
In the new research study, in which 7 people took part, the typical hearing threshold of 71 dB (3.5 mPa) is at 500 Hz. Hearing limit is the sound level below which a persons ear can not hear anything.
” It is 26 dB lower than hypothesized in previous studies, so we should conclude that human beings hear substantially better under water than previously reported by science. The limit at 500 Hz is in line with how well animals such as seals and cormorants hear underwater,” states Jakob Christensen-Dalsgaard
Worth keeping in mind in this context is, that e.g., seals and dolphins– unlike us– can hear really loud noises undersea– also sounds that humans can not hear.
The previous research studies assumed that the human ear undersea works by so-called bone conduction; that is, the sound waves vibrate the skull. That hypothesis would fit the high hearing thresholds found in previous research studies.
A human and seal underwater. Credit: University of Southern Denmark.
” But we believe that resonance in the enclosed air in the center ear amplifies the sound and makes the ear more delicate. We have likewise shown this in previous studies of frogs, turtles, and cormorants,” discusses Jakob Christensen-Dalsgaard.
” You ought to not expect to be able to delve into the sea and orient yourself completely using just your sense of hearing,” says Jakob Christensen-Dalsgaard, “Sense of hearing is not almost having the ability to choose up a sound. It is also about determining the instructions of the noise– and this is very challenging for a person undersea.”
” In the air, we can identify the sound direction within a couple of degrees, however in water, there is an approximately 90 degrees error margin. This is not so odd, because we are trained to react to the little time distinctions between the ears, which are because of the speed of noise in air. In water, the speed of noise is four times greater, and the time distinctions are much smaller sized,” Jakob Christensen-Dalsgaard describes, concluding, “The results tell us that people have actually a lowered ability to figure out the direction of noises underwater, hence validating that human hearing is not adapted to work well undersea.”
Reference: “Is human undersea hearing moderated by bone conduction?” by K.Sørensen, J.Christensen-Dalsgaard and M.Wahlberg, 19 March 2022, Hearing Research.DOI: 10.1016/ j.heares.2022.108484.

Four females and 3 men aged 23-49 years, took part in the hearing tests. The research study discovered that hear far better undersea than formerly reported.
Humans or seals? Who has the very best underwater hearing?
All mammals lived on land countless years back, however eventually, certain types adjusted and abandoned the land to life in the sea: take seals and whales, which both can now live undersea.
The rest of the types that continued on land has actually likewise adapted to a life on land. That is why it shouldnt be a surprise that a group of specialists concerned the conclusion that people today hear better on land than under water in a recent study. However, the research likewise provides unforeseen information on human hearing.
A specialist in animal hearing, Jakob Christensen-Dalsgaard commits his energy and time to studying the hearing of creatures including cormorants, frogs, crocodiles, and geckos, in addition to people, in his laboratory at the University of Southern Denmark This time, he is working along with Ph.D. candidate Kenneth Sørensen and biologist Magnus Wahlberg, who is an expert on animal undersea hearing and also attends the University of Southern Denmark.