Re: Does sound diminish in volume as you increase elevation?

As sound waves are carried by gas (air) molecules: Yes, sound propagation
diminishes with decreased density of gas. In vacuum or outer space there
is no gas, therefore no sound at all.
However, within elevation levels where humans can survive without space
suits, the athmospheric pressure varies too little to make the effect
noticeable.
Also: Since most materials (including glass) are good sound conductors,
an alarm clock in an evacuated jar is only inaudible when floating in
the vacuum without physical contact to the walls or a holder.

I hope this answers your question. Please contact me again if not.

Greetings from Singapore,
        Frank Berauer
        beppi@IndoArtNet.com