Science > Physics > locating high pitched sound - human factors or acoustics
| Topic: |
Science > Physics |
| User: |
"TimR" |
| Date: |
04 Aug 2003 06:55:33 AM |
| Object: |
locating high pitched sound - human factors or acoustics |
This weekend I heard the smoke alarm apparently go off at 4:30 am.
But none of my smoke alarms were sounding, and the noise was similar
but only about 75% as loud, and a continous high pitch rather than
pulsating.
I couldn't find it. I searched the entire house including attic
multiple times, I just could not tell what direction it was coming
from. My suspicion was a battery operated child's toy, this has
happened before. The sound was roughly equal in every room, loudest
in the upper half. There was no sound at all outside (I was thinking
the air conditioner)(or maybe very bad tinnitus - I was VERY happy it
was quiet outside). I turned off every electrical circuit without
effect. I tried localizing by blocking ears, using hands as funnels,
spinning, etc. Nothing worked.
To make a long story short (yeah, too late <grin>) about 6:00 am I
discovered it was my cheap digital wrist watch. It must reflect off
my hard plaster ceilings but disappear outside.
So what is it about high pitched electronic sounds that make it so
hard to perceive direction? Is it our ears? Or was it an interaction
with the room? Aren't there some implications for safety equipment
like fire alarms?
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| User: "Mark Fergerson" |
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| Title: Re: locating high pitched sound - human factors or acoustics |
05 Aug 2003 05:57:23 AM |
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TimR wrote:
<snip>
So what is it about high pitched electronic sounds that make it so
hard to perceive direction? Is it our ears? Or was it an interaction
with the room? Aren't there some implications for safety equipment
like fire alarms?
Spacing between your ears vs. phase difference over path
length.
And who cares where the alarm is? It is saying RUN FOR
YOUR LIFE! You have to use your onboard sensor suite to
determine a preferred direction.
Mark L. Fergerson
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| User: "TimR" |
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| Title: Re: locating high pitched sound - human factors or acoustics |
05 Aug 2003 10:32:38 AM |
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Mark Fergerson <mfergerson1@cox.net> wrote in message news:<3F2F8D93.3050403@cox.net>...
TimR wrote:
<snip>
So what is it about high pitched electronic sounds that make it so
hard to perceive direction? Is it our ears? Or was it an interaction
with the room? Aren't there some implications for safety equipment
like fire alarms?
Spacing between your ears vs. phase difference over path
length.
And who cares where the alarm is? It is saying RUN FOR
YOUR LIFE! You have to use your onboard sensor suite to
determine a preferred direction.
Mark L. Fergerson
Mark's point is well taken, even with choice of exit routes. On the
other hand, after the emergency is over, a little intellectual
curiosity about this perception effect may not be misplaced.
There has been some discussion about a similar phenomenon, strobe
lights on emergency vehicles. Now that they are so common, it has
become very difficult to locate them.
Hmmh, phase difference and the distance between your ears. That needs
some further explanation. You're in a multipath echo situation, with
wave lengths short in relation to separation. Why would low pitches
be more easily located?
By the way, several private emails have confirmed the difficulty
locating high pitched electronic sounds, but some believe the sine
wave nature is also part of the problem.
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| User: "Jim" |
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| Title: Re: locating high pitched sound - human factors or acoustics |
05 Aug 2003 10:18:30 PM |
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(TimR) wrote:
Mark Fergerson <mfergerson1@cox.net> wrote in message news:<3F2F8D93.3050403@cox.net>...
TimR wrote:
<snip>
So what is it about high pitched electronic sounds that make it so
hard to perceive direction? Is it our ears? Or was it an interaction
with the room? Aren't there some implications for safety equipment
like fire alarms?
Spacing between your ears vs. phase difference over path
length.
And who cares where the alarm is? It is saying RUN FOR
YOUR LIFE! You have to use your onboard sensor suite to
determine a preferred direction.
Mark L. Fergerson
Mark's point is well taken, even with choice of exit routes. On the
other hand, after the emergency is over, a little intellectual
curiosity about this perception effect may not be misplaced.
There has been some discussion about a similar phenomenon, strobe
lights on emergency vehicles. Now that they are so common, it has
become very difficult to locate them.
Hmmh, phase difference and the distance between your ears. That needs
some further explanation. You're in a multipath echo situation, with
wave lengths short in relation to separation. Why would low pitches
be more easily located?
They are?
Is that why sub-woofers can sit in a corner, while the other 5
speakers have placement recommendations? :)
Jim
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| User: "John Sefton" |
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| Title: Re: locating high pitched sound - human factors or acoustics |
04 Aug 2003 05:12:33 PM |
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TimR wrote:
This weekend I heard the smoke alarm apparently go off at 4:30 am.
But none of my smoke alarms were sounding, and the noise was similar
but only about 75% as loud, and a continous high pitch rather than
pulsating.
I couldn't find it. I searched the entire house including attic
multiple times, I just could not tell what direction it was coming
from. My suspicion was a battery operated child's toy, this has
happened before. The sound was roughly equal in every room, loudest
in the upper half. There was no sound at all outside (I was thinking
the air conditioner)(or maybe very bad tinnitus - I was VERY happy it
was quiet outside). I turned off every electrical circuit without
effect. I tried localizing by blocking ears, using hands as funnels,
spinning, etc. Nothing worked.
To make a long story short (yeah, too late <grin>) about 6:00 am I
discovered it was my cheap digital wrist watch. It must reflect off
my hard plaster ceilings but disappear outside.
So what is it about high pitched electronic sounds that make it so
hard to perceive direction? Is it our ears? Or was it an interaction
with the room? Aren't there some implications for safety equipment
like fire alarms?
A duck's quack does not produce an echo.
John
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| User: "tj Frazir" |
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| Title: Re: locating high pitched sound - human factors or acoustics |
04 Aug 2003 05:19:18 PM |
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Ah ..looks like the buzz affect .
smoke some ore and ask again
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