I didn't see where the VCA hospitals explained how tilting gives vertical information that is stated in the Smarter Every Day video. This was fun to see though, because watching my dog listening for movement underground (gophers, insects), and just in general, it occurred to me that a horizontal head position, only gives horizontal direction, but not whether it's above or below. Tilting solves that and 2 tilts, 90 degrees of difference, gives complete directional location. A slight rotation left or right, with one ear more forward than the other, can give range. It's amazing what a few hundred million years of evolution can come up with!
It seems obvious in hindsight, but that's an interesting insight I hadn't thought of before.
This got me curious about how we can roughly determine if a sound is coming from above or below us even without tilting our heads. A quick search led to this interesting but somewhat open-ended stackexchange answer:
> Localization in the vertical plane (elevation) is less well investigated. As far as I know it is the shape of the outer ear (pinna) that transforms the frequency characteristic of incoming sound. In terms of directional hearing it is thought that sounds coming from above lead to a different head transfer function than sounds from below. This means that localization can only be accomplished when the sound has a particular familiar characteristic that is slightly disturbed in the frequency domain when encountered at different angles of elevation (Hofman & Van Opstal, 2003). [1]
From this, it seems like the pinna is shaped in such a way that it filters audio differently depending on whether it came from above or below? Can anyone who has more experience with ears confirm or clarify this?
Here is the source they reference: https://vcahospitals.com/know-your-pet/why-dogs-tilt-their-h...