People can tell if a sound is coming from their right or left, by the small delay of the sound reaching their ears. How do people recognise if a sound comes from above or below?

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People can tell if a sound is coming from their right or left, by the small delay of the sound reaching their ears. How do people recognise if a sound comes from above or below?

In: 222

By the shape of our ears. The top 1/2 of our ears don’t look the same as the bottom 1/2.

SmarterEveryDay has a video on this, including a fun little experiment showing that if you put playdoh on your outer ears, you no longer can discern these things (4:30 mark):
https://youtu.be/Oai7HUqncAA

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It also isn’t just a delay difference between the ears, it also is an volume difference and a frequency difference caused by the sound wrapping around our skull.

Head Related Transfer Functions (HRTFs) are very important in getting headphones to sound right (especially in-ears) and super important to get spatial audio to sound right.

When Sony announced spatial audio for the PlayStation, they showed the insane rig they used to measure an individual’s HRTF:
https://youtu.be/ph8LyNIT9sg?t=2400

It is not just from the direct line from the noise to your ear.It is also from the sound bouncing off nearby objects and then reaching your ear.

Am i wrong to assume that this is the reason we tend a perceive sound underwater as coming from everywhere? The delay is lower as sound waves go way faster under water?

You actually don’t, at least not with same resolution as right-left. Destin’s testing in that Smarter Every Day vid is valid but I’d argue humans cock their heads when they hear something weird for the same reason dogs do it: getting that vertical separation gives you a *much* more precise location. In fact, I wonder if they let his son cock his head sideways that his vertical resolution would’ve improved even with the playdoh.

On top of what was already answered, you can tell some based one the vibrations felt through your body. If someone is drilling a hole on the flat above you you’ll feel it much different than someone drilling in the flat below. Your feet, legs and even torso will carry the sound from below much different than from above, and your brain is smart enough to interpret that without you even knowing.