[DoctorBeaver (OP)]

What is it that gives some animals such good hearing? Is the size or tension of the eardrum? The shape of cavities or bones? The size and shape of the outer ear? []

Please enlighten me.

[another_someone]

It rather depends on what you call 'good hearing'.

Some of it is just how their brain is wired, in the same way as blind people often have superior hearing, not because their ears are more efficient, but because their brains are better at extracting the maximum information from those ears.

Bats have a channel that links to two ears internally, and this gives them exceptional directional hearing that allows them to echo locate.

The size and tension of the eardrums might affect the frequency range the animal hears in, but I rather doubt it would effect its sensitivities.  Most of that I would imagine to be in the design of the inner ear.

[Karen W.]

I also believe as have been previously discussed that the shape of the outer ear by size and shape allows the ear to take in and trap more sound and actually that enhances the hearing also!

I want to say the thread was something like do bigger ears hear better.. something along those lines.. Hey Paul.. do you remember the name of the thread... I think Neil would remember also! May have been his thread... []

There have been a couple of them asked pertaining to this question!

[DoctorBeaver (OP)]

I also believe as have been previously discussed that the shape of the outer ear by size and shape allows the ear to take in and trap more sound and actually that enhances the hearing also!

I want to say the thread was something like do bigger ears hear better.. something along those lines.. Hey Paul.. do you remember the name of the thread... I think Neil would remember also! May have been his thread... []

There have been a couple of them asked pertaining to this question!

Well I'll just shut up then   []

[another_someone]

I also believe as have been previously discussed that the shape of the outer ear by size and shape allows the ear to take in and trap more sound and actually that enhances the hearing also!

It rather depends on the type of outer ear.

Can't say the big ears of an elephant would achieve that, but to rigid, upright, ears of a horse might help focus the sound a bit better (as much important in blocking out unwanted sounds as concentrating the intended sound).  The effect would be no different from cupping your hands around your ears.

The point is that it focuses sound, so is good for directional hearing, but not so good for omnidirectional sensitivity.  It also works better with higher frequency sounds, which typically relate to smaller animals, while being useless for the low frequency sounds that elephants would use.

[Karen W.]

I also believe as have been previously discussed that the shape of the outer ear by size and shape allows the ear to take in and trap more sound and actually that enhances the hearing also!

I want to say the thread was something like do bigger ears hear better.. something along those lines.. Hey Paul.. do you remember the name of the thread... I think Neil would remember also! May have been his thread... []

There have been a couple of them asked pertaining to this question!

Well I'll just shut up then   []

Please don't my comment was not meant to stop your post but to let you know you may find some intresting answers there too! just extra info..
+ apologise if that sounded bad...