[sdiy] ot: law for high frequency damping in air? law for high frequency damping on reflections?

[Czech Martin]

I'm now glad that I understood the 1/r law for far field sound pressure
level. (You can laugh about me).

Now, this is not the only thing that happens.

It must be SPL(r,f).

As sound travels in air, there are losses, sound waves will
heat up the air a little bit. This means:
the 1/r law assumes that no energy is dissipated, but that
the soundwave expands like a bubble, stating that energy is constant,
but the surface it travels through is expanding.

If we now introduce energy dissipation, the higher frequencies will
be damped more, how will the SPL law be: SPL(r,f)?

And: do you know how the reflection from a surface can be descibed?
Like a filter (plus traveling time)?

Cheers
m.c.