Picture this common scenario: you hear a sound, and instinctively turn your head towards its direction. Have you ever wondered how do you know where that sound is coming from?
After the popularization of navigation applications that use digital maps, many of us have lost the perception of how sound has always been an essential orientation and navigation tool. It’s the car horn alerting you to stop and look around, a friend’s voice guiding you in a crowd, or even that moment you lose your phone and ask someone to call your number - most probably finding it between the sofa cushions, after following the phone’s ring.
It’s so natural to us that we don’t notice how sound guides not only human behavior, but also other animals' daily life.
How mammals have used sound for, basically, everything
“Many marine animals rely on sound for survival and depend on unique adaptations that enable them to communicate, protect themselves, locate food, navigate underwater, and/or understand their environment. They may both produce sounds and listen to the sounds around them.” Font: Discovery of Sound in the Sea, The University of Rhode Island and Inner Space Center
It’s not only a human trait to use sound as a bridge with the world around us: many different animal species do so, and researchers have found that this is even more particular to mammals. One of the main uses of sound is clearly connected to communication. Now, you must be thinking: are whales gossiping loads throughout the ocean? Listen for yourself:
Sounds are so popularly used by mammals for communication because it makes it possible to convey a great deal of information quickly and over long distances. Especially in the case of marine mammals, like whales. Imagine the seasonal and long migrations these animals do, crossing oceans in groups: it’s important to communicate well to maintain group structure. Dolphins are known to travel in large groups as well, and to use sound to convey messages. The content differs depending on the pitch, rate, and sound structure.
Back to the whales, they use sound for more than just gossip and communication in general. As some ships use sonar systems, whales and other mammals such as bats have also developed a system to “detect, localize and characterize objects”. The system’s name is echolocation, and it can be described as:
“A physiological process for locating distant or invisible objects (such as prey) by means of sound waves reflected back to the emitter by the objects." Font: Encyclopedia Britannica
In other words: animals emit noises that bounce back from objects in the form of an echo, providing them with information about the object’s size and distance. Depending on how fast the sound travels back, they can estimate how close the object is - the faster the sound comes back, the closer the object is. The same happens with the object’s density: the more intense is the sound, the denser is the object.
Why is sound an intuitive tool for orientation
In the case of humans, there’s a big advantage in terms of how our auditory system is built. The simple fact of having two ears helps us to determine the direction of a sound.
The secret of binaural hearing, as researchers call it, is the position of the ears: by being located on opposite sides of the head, “the sounds heard by either ear will vary in timing, volume, and frequency balance (E-Home Recording)”. Volume and timing might be one of the most noticeable factors: below you can find a good example of how sound volume and timing influence our ability to detect the direction of a sound:
“A noise coming from the right is slightly louder in your right ear, and reaches it fractionally earlier than your left. A sound in front or behind affects each ear the same way, with intermediate effects in-between. The brain uses these differences, even as small as a 100,000th of a second, to calculate where the sound is coming from.” BBC Science Focus Magazine
However, volume and timing variations are not the only evidence used by our brains to locate where a sound is coming from. A third factor that researchers have pointed out is frequency:
“High frequencies have less energy, are more easily absorbed by obstructions than low frequencies. So with our unidentified sound, your right ear will get MORE of the low end, and LESS of the high end ” E-Home Recording
What the brain does in a 100.000 split of a second is to put all those factors together, determining the direction from which the sound originates. Our brain is ‘wired’ to seek where a sound is coming from for the same reason as other mammals: safety, food location, orientation. It’s instinctive, and that’s why it feels so intuitive to immediately know where a person is just by following their voice, for instance.
Is sound a better navigation tool than digital maps?
Even though scientific researchers have proved how easy it is to be guided by sound, digital maps are still the main feature of mainstream navigation apps. For the audio part, those apps offer verbal descriptions - which are completely different than using sound as orientation. They overload our brain with instructions and require extra concentration and focus.
The thing is that map reading is an acquired skill, something people need to be taught how to do. And following sounds, as we previously discussed, it’s instinctive, natural to us. After we shared the post above on Dreamwaves social media channels (are you following us yet?), a user made the comment below:
“Sound navigation feels more like a hardware (vs digital maps as a software) solution for our brain.. quicker and more reliable!”
That’s a perfect analogy, especially for the tech people out there: we already have the physical components to use sound as a navigation tool. On the other hand to read, interpret and understand a map, you need to 'download' a set of instructions, like a software you install on your computer. If you want to try how easy audio orientation is, you can download the spatial audio navigation app waveOut for free at the App Store: https://apple.co/3IXJ0UB
https://dosits.org/animals/use-of-sound/how-do-marine-animals-use-sound/
https://www.hear-it.org/The-direction-of-sound
https://www.sciencefocus.com/the-human-body/how-do-we-know-where-sounds-are-coming-from/
https://web.pa.msu.edu/acoustics/loc.htm
https://www.treehugger.com/what-is-echolocation-definition-and-examples-5118464
https://ehomerecordingstudio.com/binaural-hearing/
https://360.here.com/2014/10/06/people-better-map-reading-others/