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Sound on other planets

  1. May 29, 2008 #1
    Hey guys,

    I am no scientist (I am studying advertising at uni), although I am terribly interested in it. My highest scientific learnings was highschool; but I did take physics, math c, biology, chemistry. Anyway, I am in no way qualified so my point is bear with me and don't hate ;)

    I was just pondering tonight and I was thinking about space, aliens and other stuff you think of at night :P

    And I got to wondering, my crude knowledge of sound is it is vibrations of air that our ears then turn pick up, turn into electrical signals, and our brains translate.

    Now I know, or am assuming (incase it has been disproven and I don't know :) ) that there is no sound in space because there is no air. So on other planets, where the air is different, is sound then different? On mars is sound higher pitched or lower?

    And just being far fetched, but assuming an alien environment is so unlikely to be exactly the same as ours, would an alien be even able to hear us - or us them.

    But I accept stupid questions deserve stupid answers. So if this is stupid to you, apologies and flame away.
  2. jcsd
  3. May 29, 2008 #2


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    Staff: Mentor

    There will be differences in pitch (like when speaking in helium, or sulfur hexafluoride), but in general - as long as aliens use the same frequency range (ie they don't communicate with ultrasounds) there should be no problem with hearing them.
  4. May 29, 2008 #3
    A sort of example

    Have you ever heard someone talking who has been breathing helium? So on a helium world (unlikely!) anything that makes a sound due to resonant cavities would sound higher pitched e.g. voices, resonant empty containers. For solid objects which make a sound without any cavity been involved e.g. hitting a block of wood with a hammer, I think these would still make the same noise. But In practise any enclosed space such as a room, also has its own affect on the sound in terms of reverberation and resonance. So the after effect of hitting a block of wood with a hammer on the helium world,(the echo or dying away bit), would undergo a similar effect to the way a voice is modified breathing helium. Probably.
  5. May 29, 2008 #4
    Yeah I assumed it would change pitch like those gasses do here. But I was just wondering if this had any implications. Is the atmosphere much different on say Mars, where future humans on Mars would speak differently then those on Earth. Would prolonged speaking in such an environment cause any biological effects like say speaking more softly or the ears changing etc.

    Just seems movies always take sound out of the picture and you never 'hear' about it. *pun seriously not intended, but lol*
  6. May 29, 2008 #5
    The denser the medium the better the soundwaves propogate. So is it the denisty of the medium that controls the pitch of the sound? For example helium is less dense then air by alot so the sound is more high pitched, a denser medium then air such as water creates a more low pitched noise, or am I remebering my phyics inaccurately?
  7. May 29, 2008 #6
    If it's an atmosphere that humans can live in I guess its going to be pretty much like the air here anyway.
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