PSN-L Email List Message

Subject: Re: Noise
From: ChrisAtUpw@.......
Date: Thu, 23 Nov 2006 16:39:10 EST


In a message dated 2006/11/23, tchannel@.............. writes:

> The sensor, a Lehman, is in my basement. It is on a concrete floor next to 
> a concrete wall, and the house above is wood and brick.
> Could this noise be the sun?  At about the time the noise begins the sun 
> rises above the trees and shines on the east side of our house, which is also 
> the wall near the sensor.

Hi Ted,

       Next to the concrete wall may not be the best place? General advice is 
to keep sensors away from walls.

       Does the house 'creek and groan' at all during the day? If it was 
direct sun on the house and things moving, I would expect you to be able to hear 
them, at least sometimes, if you try. Maybe run an audio tape recorder on high 
sensitivity in the basement to include one or more events? However, I would 
also expect house noise to be related to wind conditions.

       Now you have got the Lehman cosily enclosed in a thermally insulated 
airtight box haven't you?

       What is the construction of the Lehman suspension, top and bottom? 
What detector are you using? 

       Do you have central heating or electrical appliances which come on 
between 8am and 5 pm? These times do sound suspiciously like work day activity of 
some type, or related to it in some way. Do you get increased environmental 
noise between these times? 

       Do you have a geophone? I got mysterious thump type signals 
intermittently, of short but varying length, which did not seem to be related to 
anything obvious. I eventually connected an audio amplifier and headphones up to one 
of the geophones - no seismic amplifier. I found that I could hear fast 
traffic on the main road starting at ~1 km. The thumps seemed to be directly related 
to lorries when travelling round a bend in the road. When I checked the road, 
I found a sunken drain grating on the inside of the bend. When there was 
traffic in both directions, lorry drivers kept tight to the inside of the bend and 
ran over the recessed grating. I pointed out this traffic hazard to the 
authorities and they replaced the drain cover....

       Regards,

       Chris Chapman
In a me=
ssage dated 2006/11/23, tchannel@.............. writes:

The sensor, a Lehman, is in my=20= basement. It is on a concrete floor next to a concrete wall, and the house a= bove is wood and brick.
Could this noise be the sun?  At about the time the noise begins the s= un rises above the trees and shines on the east side of our house, which is=20= also the wall near the sensor.


Hi Ted,

       Next to the concrete wall may not be th= e best place? General advice is to keep sensors away from walls.

       Does the house 'creek and groan' at all= during the day? If it was direct sun on the house and things moving, I woul= d expect you to be able to hear them, at least sometimes, if you try. Maybe=20= run an audio tape recorder on high sensitivity in the basement to include on= e or more events? However, I would also expect house noise to be related to=20= wind conditions.

       Now you have got the Lehman cosily encl= osed in a thermally insulated airtight box haven't you?

       What is the construction of the Lehman=20= suspension, top and bottom? What detector are you using?

       Do you have central heating or electric= al appliances which come on between 8am and 5 pm? These times do sound suspi= ciously like work day activity of some type, or related to it in some way. D= o you get increased environmental noise between these times?

       Do you have a geophone? I got mysteriou= s thump type signals intermittently, of short but varying length, which did=20= not seem to be related to anything obvious. I eventually connected an audio=20= amplifier and headphones up to one of the geophones - no seismic amplifier.=20= I found that I could hear fast traffic on the main road starting at ~1 km. T= he thumps seemed to be directly related to lorries when travelling round a b= end in the road. When I checked the road, I found a sunken drain grating on=20= the inside of the bend. When there was traffic in both directions, lorry dri= vers kept tight to the inside of the bend and ran over the recessed grating.= I pointed out this traffic hazard to the authorities and they replaced the=20= drain cover....

       Regards,

       Chris Chapman

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