Why are our ears shaped the way they are with all their weird ridges? Why aren’t they more simply shaped like a funnel?
In: Biology
This actually has to do with sound localization– our ears being shaped weirdly enables us to be better at determining where in our three-dimensional world a sound is coming from.
The two primary ways that enable an individual to localize sounds in space are sound arriving at your ears at slightly different times, and at slightly different levels of intensity. I won’t go into the gory details here, but if you want a full rundown of sound localization, I encourage you to refer to [this](https://www.reddit.com/r/explainlikeimfive/comments/dtgkp3/eli5_how_do_we_percieve_the_direction_in_which_a/f6wnun6/)
But anyways, given that we mainly perceive sound through differences in time and intensity of the sound reaching our ears, that leads to a bit of a problem.
There’s this concept called a “cone of confusion.” Imagine a clock around your head, with 12 o’clock directly in front of you, and 6 o’clock behind you.
Imagine a tone at 10 o’clock, and a tone at 8 o’clock. The difference in time and intensity these sounds will reach your ears at will be identical, so theoretically you wouldn’t be able to distinguish where a sound was coming from– in front of or behind you. In fact, if you imagine a sound at 10 o’clock, you can move that sound up or down in an arc and it would suffer from the same problems. In this way, there is a sort of “cone” where any sounds within the cone have the same time difference and level difference, and you’ll be able to localize them in space (hopefully you see what I’m talking about here). This is called the cone of confusion, and it’s a real thing. You have infinitely many cones of confusion all nested within one another, and any 2 sounds that are in the same cone of confusion are hypothetically unable to be distinguished from each other.
Confused? Hopefully this image helps clarify–[this](https://www.researchgate.net/profile/Bill_Kapralos/publication/257764036/figure/fig2/AS:297648201453572@1447976269745/Cone-of-confusion-A-sound-source-positioned-on-any-point-on-the-surface-of-the-cone-of.png)
Luckily, we have mechanisms to deal with sounds lying within the same cone of confusion. The easiest way to deal with it is just to move your head a little bit. However, another “trick” your body has to deal with cones of confusion is that sounds are funneled into your ear differently depending on where the sound is in space.
The outer, squishy, cartilage bit you’re talking about in your question is called the pinna of the ear. Everyone’s pinna is shaped differently, and so funnels sound differently into the ear depending on where it is If I play a sound and move it around your head, you’ll perceive the sound as changing in loudness, even if its the same absolute distance from your head. This is because your ears and upper body will filter the *same* sound differently depending on where in space it is.
What do I mean by this? Imagine you’re in a room with absolutely no sounds except magical speakers floating around. Imagine that I put a microphone into your ear, right next to your ear drum. Imagine one of these speakers floats somewhere on your left side, slightly above your head. I get this speaker to play sounds of different frequencies at the same loudness. The microphone inside your ear canal actually won’t record the same intensity for all the different frequencies– at any point in space, different frequencies are “better” at making it to your ear. This is called the directional transfer function, or DTF
This is another “trick” your brain uses to help localize sounds– you subconsciously know your unique DTF, and you can use it to judge where sounds are.
Latest Answers