Does anyone know if Pinnae Size has any effect on ear sensitivity and echolocation?

Intuitively, I'd imagine so. It probably has a lot to do with the shape too. I don't know what all those echolocating bats would be doing with their large pinnae if they didn't have some effect on hearing.

The shape and location of the pinna most certainly impacts both those things. A lot of the "echolocation" part is from comparing the difference in signals between the two ears. Much like we can see 3 dimensions with our two eyes, we can locate sound by interpretting the difference in signals arriving to the right ear from the signals arriving to the left (clearly, one ear will be closer to the source, and that difference in placement can provide valuable information about its location). I'd also suggest that the cochlea plays a critical role.

 

http://en.wikipedia.org/wiki/Pinnae

 

http://en.wikipedia.org/wiki/Cochlea

 

 

Another interesting area to consider would be the cilia, the small hairs suspended in the fluid of the inner ear. The pressure wave from the sound causes them to bend, and that bending triggers the chemoelectric response of the nerve cells, generating the neural signal which travels to the brain.

 

http://en.wikipedia.org/wiki/Stereocilia_(inner_ear)

 

 

One of my favorite classes in college was Perception. While we covered a lot of philosophical viewpoints, we also spent several weeks on anatomy and physiology.