Reduction of noise from baseboards

bordercollie
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Reduction of noise from baseboards

Postby bordercollie » Sat Dec 07, 2019 8:52 am

Hi

I have been looking at the "plywood disaster" thread.

From what I can understand, it is widely accepted that once the the ballast has been glue down using either cork or closed cell rubber as underlay, that conventional methods result in, what many people consider to be annoying levels of noise. This being due to the baseboard material acting as a "drum".
I was reading a thread on another forum that suggested using a sound deadening material such as curtain material hung from baseboard down to the floor would at least reduce the noise. I would imagine the thicker the material the better. Has anyone used this method and does it work?

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Le Corbusier
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Re: Reduction of noise from baseboards

Postby Le Corbusier » Sat Dec 07, 2019 9:33 am

When we are looking to address acoustics, there are generally two different aspects we look to mitigate ... airborne sound and impact sound through the structure. Airborne sound is managed by a mixture of absorption and sealing. Impact sound (drum like) is dealt with by a mixture of isolation, damping and mass. I suspect the main problem with track noise is one of amplification through the structure ... particularly when a thin plywood skin is involved. The fact that the glue and ballast mix appears to destroy any isolation which previously existed between the structure and the track, and because the 'drum' structure has been dictated by the need to keep weight down, damping is all that is left to us. This could be achieved by packing the voids with wadding, .... I also think that the sound deadening approach now taken in motorcar bodywork might also be quite effective where portions of deadening material are bonded directly to the skin. https://www.vwheritage.com/camper-van-camping-accessories/stp-sound-deadening-insulation

Curtain material hung to the floor might have some deadening effect as it would absorb the airborne sound from beneath the layout and to some extent would mitigate sound leakage, but I would be surprised if it had a big effect.

Those would be my thoughts, for what they are worth.
Tim Lee

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LesGros
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Re: Reduction of noise from baseboards

Postby LesGros » Sat Dec 07, 2019 9:54 am

:idea: Has anyone tried using egg trays( papier Mache) under the base boards?

:?: If so, was it effective?
LesG

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Tim V
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Re: Reduction of noise from baseboards

Postby Tim V » Sat Dec 07, 2019 10:35 am

As I pointed out in the other thread, it isn't the baseboards that are noisy, it is poorly engineered stuff running on top of it.

Look there first - remove those XO4s (and the like), fit properly engineered bearings, decent gearboxes, decent motors. Plus controllers that don't make the motors buzz with feedback (DCC is good at eliminating this ...).

Or you could do none of these and just turn up the stereo in the railway room :D
Tim V
(Not all railways in Somerset went to Dorset)

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Will L
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Re: Reduction of noise from baseboards

Postby Will L » Sat Dec 07, 2019 12:35 pm

And springing your stock significantly reduces the drumming effect.

bobwallison
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Re: Reduction of noise from baseboards

Postby bobwallison » Sat Dec 07, 2019 6:26 pm

Noise bounces off hard surfaces and reverberates around the room, but is absorbed by soft materials. When my acoustic colleagues were asked to deal with excess noise in trendy restaurants, they advised cutting down the reverberated noise by replacing hard furniture and decor with soft: it worked a treat.
So yes, I think heavy-ish curtains would help reduce the overall noise level, as would soft floor-covering, but I couldn't begin to guess what percentage improvement you might expect.
I cannot vouch for the noise-attenuating properties of teddy bear fur after it has been dipped in green paint....

Regards,
Bob

Terry Bendall
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Re: Reduction of noise from baseboards

Postby Terry Bendall » Sun Dec 08, 2019 9:27 am

Noise can be a problem but in my experience only for layouts used at home. All the layouts I have been involved with have been designed to take to exhibitions and when testing at home the noise is evident. However, in an exhibition hall the ambient noise in the hall from visitors cancels out any noise from the layout. A few weeks ago Elcot Road was shown at an exhibition held in a school with most of the layouts in classrooms, so a much smaller space than usual. Even with a few visitors in the room - more than 8, the noise was not apparent. This would support the point Bob puts forward about soft surfaces absorbing sound.

For layouts used at home, and which are in a bedroom or loft space, the noise could we be annoying for those in rooms below, but in other spaces it is probably liveable with.

I am not convinced that all the noise is due to the mechanism and bearings of the locos. At home there is not sufficient room in my workshop to set up the fiddle yard with the rest of the layout so for testing a small fiddle yard is used. This has two lengths of plastic sleepered track just fixed down at the ends with the rest sitting loose on the top surface. Locos are quiet on the fiddle yard but there is far more noise when they run ionto the layout itself where the track is glued to cork and ballasted with scale granite chipping fixed with PVA glue.

Terry Bendall

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Le Corbusier
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Re: Reduction of noise from baseboards

Postby Le Corbusier » Sun Dec 08, 2019 1:38 pm

Soft materials with depth will absorb sound .... they will not lessen the sound at source, but rather they impact on the reverberation or echo. Hence you put acoustic wadding on a wall or ceiling if you have a hard floor surface to stop the space echoing. People and books (as in a library) have a similar effect ... so less absorption is required in a packed theatre than would be the case if it were empty. Absorption will also to a minor extent reduce sound transference into adjacent spaces ... though the sound will be free to travel through any clear gaps (if you have two parts of a room separated even by thick floor to ceiling curtains, you can still hear pretty clearly what is being discussed!)

So absorption per se is not particularly good at preventing transmission of sound ... it just stops the original sound being reinforced or amplified. Once you have above a certain number of people in a hard surface space it becomes difficult to hear yourself speak because of sound reflection... so absorption becomes desirable ... the volume of the original sound input remains pretty much unchanged.

If the sound is coming from a mechanism such as the loco wheels and is transferring noise and vibration from above into the structure of the baseboard, then springing will prevent to some extent the transfer of this noise, but as the motor is floating on the axle (in most instances) and so not part of the sprung weight, it will not isolate the motor noise from the structure. The structure then amplifies the noise (like an echo does) by keeping it alive and overlaying it. The best solution is obviously to decouple the track from the baseboard, which would achieve the greatest minimisation (This I suspect is what is happening with Terry's fiddle yard). However, if you like hearing the sound of wheels on rails, then decoupling the upper body via springing will serve to some extent to reduce the overall volume.

If you accept that sound is being transferred into the structure causing amplification, then the next thing to consider is how you might restrict that amplification.

If you want to minimise the transfer of sound through the structure, then giving that structure some mass will help, or alternatively providing a degree of damping to stop the drum effect of a lightweight construction.

Following on from this, hanging fabric beneath to absorb the sound once it has exited would be the next strategy. Absorption will both stop any further amplification via reverberation in the enclose volume below the baseboards and will also muffle the amplified sound before it can exit from below.

Just a few thoughts.
Tim Lee

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Rod Cameron
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Re: Reduction of noise from baseboards

Postby Rod Cameron » Sun Dec 08, 2019 2:54 pm

LesGros wrote::idea: Has anyone tried using egg trays( papier Mache) under the base boards?

:?: If so, was it effective?


Is that before or after installing all the wiring? :shock:
Rod

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LesGros
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Re: Reduction of noise from baseboards

Postby LesGros » Sun Dec 08, 2019 2:57 pm

Rod,
Just an enquiry, but probably after, and in a way which would allow removal/hinging to one side for access.

cheery,
LesG

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Will L
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Re: Reduction of noise from baseboards

Postby Will L » Tue Dec 10, 2019 6:37 pm

Obviously useful to have an architect with real knowledges on this one. Bet it feels satisfying to be the expert occasionally Tim.
Who wrote:...If the sound is coming from a mechanism such as the loco wheels and is transferring noise and vibration from above into the structure of the baseboard, then springing will prevent to some extent the transfer of this noise, but as the motor is floating on the axle (in most instances) and so not part of the sprung weight, it will not isolate the motor noise from the structure...

Fair point, so clearly if you mech grinds (Sharman spur ears were really good at this) or whines (like all but the first generation of Portescaps) springing will not help. However highlevel gearboxes (and the motors usually attached to them) are pretty quiet so that's need not be a significant part of the problem.

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Le Corbusier
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Re: Reduction of noise from baseboards

Postby Le Corbusier » Tue Dec 10, 2019 10:50 pm

Will L wrote:Obviously useful to have an architect with real knowledges on this one. Bet it feels satisfying to be the expert occasionally Tim.


With the Caveat the I am not and acoustic engineer, though I know couple with whom I work on a regular basis .... I am reasonable on the theory - but the engineers do the calcs and advise on the specifics .... though again my best guesses are getting quite good. ;)
Tim Lee

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Serjt-Dave
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Re: Reduction of noise from baseboards

Postby Serjt-Dave » Wed Dec 11, 2019 11:13 am

Just adding my penny's worth to this. Having only recently been able to run trains all the way around my layout I was quite surprised how noisy it was, except where I have used Flexi-Track then it's totally silent. When I'm running trains around the layout I have to look up when the train hits the Flexi-Track to check that nothing has derailed. The Flexi-Track runs on rubberised cork which covers the entire baseboard, where the scenic track just runs on a rubberised cork track bed. I'm hoping that as scenic items are added the noise will rebate.

Dave


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