Cat's Ear Pockets: Acoustic Advantage or Benign Evolution?

[Danger]

Cat's ear "pockets"

This is of no particular importance, but it's been bugging me for several years. I'm hoping that a biologist (or possibly an audiologist) can be of assistance.
Do the little split-edged 'pockets' on the lower outer portion of a cat's ears offer an acoustic advantage, or are they just a benign leftover of evolution?

 

[Denton]

They're probably the same as our earlobes: useless.

 

[tchitt]

I always wondered that too. Like Denton, I assumed they were the cat equivalent of human earlobes. That's just my assumption, though... I'm certainly neither a biologist or audiologist.

 

[hypatia]

I believe its to help them capture sounds, when they need to pull their ears back. I think it gives them a bit more flexibility.

 

[Danger]

Hypatia, I believe that you're on to something there. I just played with Lucy's ears a bit to check, and those flaps 'accordion' into themselves when the ears flatten. Thanks.