Anyone who knows about the physics of how sound travels?

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   DzyMsLizzyposted 11 years ago

   Anyone who knows about the physics of how sound travels?
   
   I have a chiming clock, which has an electronic chime. Those don't go out of tune. 
   However, though it sounds perfect in the same room, when heard from down the hall in another room, it sounds off-key; about a half-step flat.
   Any idea what might cause this effect?

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   Bob Bambergposted 11 years ago

   Which do you believe, the off-key clock or your lying ears?    Sound travels in waves, which, inside a building, can be distorted by features such as doorways, furniture, etc.  Perhaps you're hearing a slightly distorted chiming.

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   tsmogposted 11 years ago

   I agree with Bob and add time to be considered. The time and the space traveled should be considered. There is always the illusion of sight, sound, and memory too. When you see the clock strike the hour your memory of tune or song is more than likely heard 'in a sense' with recall before the tune itself is actually played. An illusion does occur as to the perception, which is the sensing or feeling, of being heard. Or, memory may be distorted with actuality. Whereas, the perspective or the rational of logic with evidence may be an entirely different affect upon experience or experiencing the realized sound.
   
   That concept may be validated or not and too the tick of the tock may trigger a memory of the tune sooner than the heard or sensed tune too. Much to think and ponder. Maybe for fun you are actually hearing the 'real' sound in another room not tainted by an illusion and it really is off tune. Even though stated "those don't go out of tune" I do not accept that as a truth. But that is just me. Playing the 'what if' of the thought process maybe it is never perceived as off tune in the same room. Maybe recording and looking at the wave lengths on a free recording download would help offer a solution for fun and experimenting. Hmmmm . . . . just playing a little with pondering a solution.
   
   tim

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      Bob Bambergposted 11 years agoin reply to this

      Very interesting point!

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      tsmogposted 11 years agoin reply to this

      Thank You Bob. I was just playing in a sense remembering a long time ago. My thought came from how a car sounds at the Drag Races going by at 300MPH does not sound like it really sounds like. And, the different places along that route of travel.

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      DzyMsLizzyposted 11 years agoin reply to this

      tsmog, it sounds as if your race car analogy is about the Doppler effect; how sound seems to change pitch as it passes by you, first approaching, then receding into the distance....
      The clock is not moving; nor does it have a "tick-tock" sound. ;-)

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      tsmogposted 11 years agoin reply to this

      hmmmm . . . I will have to open a science book instead of postulating However, and with jest, maybe just taking a half-step will bring it back into tune

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   Doc Snowposted 11 years ago

   Distance won't do that, but changes in relative velocity can--were you walking when you noticed the pitch shift?
   
   It's called the "Doppler effect," and the classic acoustic instance is the sound of a train whistle, which is higher approaching you and lower receding.  It's not specific to sound, though:  the same phenomenon is responsible for the red-shifts of the spectra of stars as they recede from us due to the expansion of the universe.
   
   Also, and theoretically at least, temperature differences could cause some pitch shifting.  That's because frequency depends on the speed of sound, which changes with temperature.  But off the top of my head, I doubt that the effect would be as large as the semitone you mention for an reasonable temperature differential between rooms.
   
   Finally, I wonder if the change could be due to greater attenuation of higher frequencies making a 'lower' sounding tone--sort of an audio illusion, if you will?  Sometimes psychoacoustics are sort of slippery...  it's a theory, anyway!

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      DzyMsLizzyposted 11 years agoin reply to this

      Yes--I mentioned the Doppler effect in a comment above.  And no, I was not walking; I was lying still in bed.

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