Does altitude change the sound of speakers??

I moved from 800' to 7220' about a dozen years ago, and do not recall any significant change in speaker sound due to altitude. The ability to listen at volume levels that do a system justice was an improvement very much more readily noticeable.

I do have a premium system in my truck and I experience substantial altitude changes in my travels. What I notice is that my ears plug up and things overall don't sound right. After I clear them, everything sounds much better. Meaning that there are other factors involved and I can't discern any change in the sound of the speakers directly due to attribute.

Humidity also a factor. 

The effects of gravity are reduced at higher altitudes. Thus, it is slightly possible that a speaker cone will behave slightly different at high altitudes compared to sea level. It would not be audible.

I’m high in the Rockies and everything sounds very fine.
Lightning sucks big time up here though. It’s closer!