How we work out the distance of something we can hear but not see has been somewhat of a mystery - until now . Scientists say we know how far away the source of a sound is by listening to the echoes it produces . In a study they found that the reverberations of sound help us locate the distance of , for example , a car passing round a bend or a person nearby . Scientists at the University of Connecticut say we know how far away the source of a sound is by listening to the echoes it produces ( stock image shown ) . In a study they found that the reverberation of sound helps us locate the distance of , for example , a car passing round a bend or a person nearby . The research was conducted by scientists from the University of Connecticut and published in the Journal of Neuroscience . They said that echoes and fluctuations in volume are the cues we use to figure out the distance between us and the source of a noise . Researchers have long understood how we can tell a sound 's direction - whether it 's to our left or right , front or back , and above or below us . From their heavy build and short limbs , to the shape of their skull and teeth , there are many ways that the anatomy of Neanderthals differed to our own . Now experts say that even a small bone in their ears are dissimilar to one in modern humans , raising the prospect that our extinct ancient relatives heard differently to us too . Researchers created a computer model of the middle ear bone of a Neanderthal child , whose remains were discovered in France 40 years ago . The remains from the two-year-old child , which are known as La Ferrassie 8 , were discovered at La Ferrassie in the Dordogne , south western France , between 1970 and 1973 . Asier Gómez-Olivencia , an Ikerbasque researcher at the University of the Basque Country in northern Spain , produced a 3D computer reconstruction of the remains . His work , published in The Journal of Human Evolution , reveals another anatomical difference between the Neanderthals and modern humans in the smallest ossicles of the body . But how we tell how far away it is had remained a mystery . 'The third dimension of sound location was pretty much unknown , ' said Dr Duck Kim , a neuroscientist at UConn Health . The researchers suspected that the effect echoes had on volume - or amplitude modulation - could be key in our ability to perceive a sound 's distance from us . To explore the idea , they used tiny microphones to record the sounds inside rabbits ' ears as they played sounds at different locations . They used these recordings to simulate modulated or unmodulated noise coming from different distances from the rabbit . Then the researchers played the simulated sounds back to the rabbit , and measured the responses of neurons in the rabbit 's inferior colliculus ( IC ) , a region of the midbrain known to be important for sound perception . When the rabbit heard the simulated sounds , certain types of IC neurons fired more when the sound was closer - when there was a bigger difference between the sound 's maximum and minimum volume . The farther away the source of a sound is from a listener , meanwhile , the more echoes there are , and the more limited the changes in volume become . As the source moved further away , therefore , the neurons fired less and less . The researchers say that the effect echoes have on volume - or amplitude modulation - could be key in our ability to perceive a sound 's distance from us . Without amplitude modulation , for example in an anechoic ( echo-free ) room , pictured , a person ca n't tell how far away a noise is from them . The results suggest that , as a sound gets further away , our brains are able to work out the differences in its maximum and minimum volume - and thus its distance . Dr Pavel Zahorik , a researcher at the University of Louisville School of Medicine , got the same results with human volunteers . Without amplitude modulation , for example in an anechoic ( echo-free ) room , a person ca n't tell how far away that noise is . 'Reverberation is usually considered a bad thing , ' detrimental to hearing clearly , said Dr Shigeyuki Kuwada , co-author on the University of Connecticut study . 'But it is necessary and beneficial in order to recognise distance . ' The researchers hope to investigate the problem further , and tie together the perception of distance , horizontal and vertical directions of sound .
University of Connecticut study reveals how we can measure distances . They said that listening to echoes tells us how far something it . When a sound is close the differences in max and min volume are obvious . But when you're further away, they say there's less difference between them