Subject:
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Re: Interesting audio puzzle
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Newsgroups:
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lugnet.off-topic.geek
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Date:
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Mon, 8 Jan 2001 19:12:23 GMT
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Viewed:
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123 times
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Steve Bliss wrote:
>
> In lugnet.off-topic.geek, Frank Filz wrote:
>
> > Over the weekend I experienced a puzzing thing with my home stereo
> > system.
> >
> > My stereo system includes a powered subwoofer, which started humming
> > when I stepped or stood in various places in my apartment. The stereo
> > was on, but the CD playing was paused at the time. At first I thought
> > the noise was a neighbor, but I quickly realized that it was
> > synchronized with my steps, and then experimentation showed several
> > locations where I could step or stand to cause the effect. Some
> > locations only aroused a short tone in conjunction with placing my foot
> > down in a spot, but many locations resulted in the tone continuing while
> > I stood on a spot.
>
> > Any thoughts? Any ideas for experiments to try to understand it better
> > (unfortunately I don't have an osciliscope to monitor the subwoofer).
>
> Umm, did you verify this with two people in the room? One moving about,
> one sitting still. It could be that the noise wasn't changing, but as you
> moved about the room, you were moving in and out of zones where the noise
> was audible.
>
> Sounds a bit farfetched, but so do the other explanations.
No it was just me, but the "hot" spots were definitely on the floor. In
some I could rock very slightly and turn on/off the sound. They were
also within a few feet of the subwoofer so it seems like there would
have to be some real complex wave patterns for there to be noticeable
dead spots and hot spots. I also couldn't hear anything with my head
right next to the speaker if I wasn't standing on a hot spot.
I definitely need to try some more experiments, but I'm pretty convinced
the effect was real, and is related to the floor. I can play with
tilting my body etc so that I can move my head around to eliminate the
possibility of it being a characteristic of the sound waves and not an
input to the amplifier.
--
Frank Filz
-----------------------------
Work: mailto:ffilz@us.ibm.com (business only please)
Home: mailto:ffilz@mindspring.com
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Message is in Reply To:
 | | Re: Interesting audio puzzle
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| (...) Umm, did you verify this with two people in the room? One moving about, one sitting still. It could be that the noise wasn't changing, but as you moved about the room, you were moving in and out of zones where the noise was audible. Sounds a (...) (24 years ago, 8-Jan-01, to lugnet.off-topic.geek)
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