|MadSci Network: Physics|
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
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