Help with understand noise test results?


Postby Rippley » Tue May 20, 2008 2:22 pm

I've moved into an 18 month old conversion flat and one of the biggest problems for me has been the noise/banks/rattles/creaks when my neighbour moves around/walks in his flat above me. The noises are loud enough for my sleeping patterns now to be completely out of synch as I'm woken up from sleep or prevented from falling asleep if he is in. I am completely at my wits end.
My neighbour next door in a similar basement flat has the same experience of noise disturbance as I do and his neighbour above has carpet/underlay over the floor whereas my neighbour above has fitted laminate wood flooring.
My Housing Association has done some post completion noise tests as a result of our complaints but the test between my bedroom ceiling and the floor of my neighbour above are I think totally bizarre as they come out more then best in the results. Wondered if someone could help me understand why?

Apparently the test result given for 'impact' noise in my bedroom was '27dB' @3150Hz yet I have the worse problem in this area throughout the building. All the other flat ceilings/floor results were given as passing with dB values taken @100Hz or @160Hz.

I was not in addition given a comparative test result taken @100 or @160Hz and I've asked my H.A. to explain: were any tests carried out between my ceiling and the the floor above @100Hz or @160Hz just as for the other flats tested. I've then asked them if not then why not and why my bedroom was only tested @3150Hz and as a result passed so amazingly better then the regs require (64dB max value I think for impact so you can see the difference!).
Basically- is it possible to have a favourable test result at one end of the Hz spectrum (3150) and an unfavourable one at the other (100-160) or is taken as read that a pass applies to all other values?
These differing Hz figures make it very difficult for a 'lay person' to make informed comparisons especially as I don't know how to relate an 'impact' acoustic test result of '27dB' @3150Hz to one taken/passed @100Hz or in fact how to relate this result to the constant noise that I experience/suffer.

Any deciphering advice gratefully received.


:?
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Postby Perry525 » Thu May 22, 2008 5:10 pm

You will probably accept that a child can hear things that an adult cannot.
As we get older our hearing range decreases and we loose the high notes.
Our hearing was developed at a time when our life often depended on the noise from the crack of a twig. So the normal range is ordinary sound.
That is why many people cannot hear the siren on a police car or fire engine.
Music ranges from the low of a great organ around 40 to the high of about 12,000. Below 40 we tend to feel sound, above 12,000 it tends to disappear.

I would suggest a trip to Maplin to buy a sound/noise meter, its best to do the testing yourself - then you know what is happening.

If this is a recent conversion, it should comply, however, a lot of council officers cannot be bothered. Have you ever heard of a new house failing its test and being pulled down, failure is just ignored.

Recently the Building Research people at Watford tried to build a green house to class 6, they failed, they tried again and failed again.

There is little hope, few builders have any real experience of converting a property and then living with the result.
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Postby Rippley » Fri May 23, 2008 8:12 am

Thank you for your input/comments.

I've been doing more research and it seems there is evidence to show that the tapping machine used for impact noise testing does not recreate the sound of footsteps or flexing from the movement of the ceiling/floor or the rattling of objects on shelves as someone walks overhead. Also that the Hz frequency for the sound of footsteps is usually in the lower Hz range- not the top (@3150 which is where they say my ceiling has passed by an extraordinary to the point of being suspicions margin).
I'm convinced that they have literally engineered the results by not giving me the readings for the tests taken at the same level of Hz as my neighbours (100-160Hz) because if their flats passed at that level of Hz- then why didn't mine at a similar range. ?

In addition, they say they have only used a waterproof cement render on the Victorian brick party separating walls between 20-30mm thick (30mm over the removed chimney brest area) which they insist is adequate separating party wall sound-proofing.
1) Having put up some shelves/pictures I'm pretty sure this depth has not been applied.
2) This was not tested at any stage according to Schedule E and
3) I have not found any evidence for it being a tried and trusted sound insulation application or a Robust Design method (that doesn't require pre-completion testing).

As they are a H.A. and they are responsible for the flat conversions- I'm going to have to make a complaint as I no-longer sleep when I want to and for as long as I want to and it's ruining my health and driving me crazy!
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Postby Rippley » Tue Jul 07, 2009 2:46 pm

Hi- If anybody reads this thought I'd let you know I was barking completely up the wrong tree!
In my previous posts I wrote:

"Apparently the test result given for 'impact' noise in my bedroom was '27dB' @3150Hz yet I have the worse problem in this area throughout the building. All the other flat ceilings/floor results were given as passing with dB values taken @100Hz or @160Hz."

and:

Posted: Fri May 23, 2008 8:12 am
Post subject: Help with understand noise test results?

"Thank you for your input/comments.

I've been doing more research and it seems there is evidence to show that the tapping machine used for impact noise testing does not recreate the sound of footsteps or flexing from the movement of the ceiling/floor or the rattling of objects on shelves as someone walks overhead. Also that the Hz frequency for the sound of footsteps is usually in the lower Hz range- not the top (@3150 which is where they say my ceiling has passed by an extraordinary to the point of being suspicions margin).
I'm convinced that they have literally engineered the results by not giving me the readings for the tests taken at the same level of Hz as my neighbours (100-160Hz) because if their flats passed at that level of Hz- then why didn't mine at a similar range. ?"

Correction:
It wasn't the Hz values that was significant in this instance (although I have learned that typically footfall and the kind of noise I endure seems to be mostly in the lower end of the Hz band) - it was the [b]27dB[/b] for the impact test in the bedroom.

The experienced/regulated sound company employed by my landlord to do the original tests apparently carried out impact tests on thick carpet with underlay- that was why the test results taken in a similar flat were approx 20dB different!
Once I discovered my neighbour above had carpet in his bedroom I did some research (see Napier University ref below) and it all started to make sense.
The results from doing impact tests directly on carpet/underlay in the flat above virtually matched the laboratory results and that's what led to my discovery that the tests had been significantly 'improved' by the flooring surface.
New tests have since been carried out that were done on a board (not directly on the carpet) that apparently is the/a recommended way to do it in a furnished/lived in property (if the original flooring surface is not exposed etc.). It still didn't fully recreate the 'flexing'/rattling of the ceiling but at least it showed a more realistic impact test result and some of the noise I experience was audible to the second lot of test engineers this time round.

A good site to learn more about understanding what sound tests mean (with laboratory results for different flooring examples) can be found in a report carried out by Napier University for DEFRA, I think it was published in 2005.

"Development and Production of a Guide for Noise Control from Laminated and Wooden Flooring" Google "defra.gov.uk/environment/noise/research"

If it hadn't been for this then I couldn't have put up a reasoned argument to my landlord as to why I was unhappy with the 'remarkable' test results and got them to do more tests.

I hope this info helps someone else? :)
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