Noise Cancelling an entire room

[Barneel]

I'd be interested to understand more on this topic as I have an ongoing project that would benefit from something like this.

Noise Cancellation (without headphones)

I have a large room, and in the corner is a large control system with large amounts of cooling fans, drives, motors and other components, making a lot of noise. There will only be one person in the room with the control system at any one time. The position of this control system (and therefore the source of the noise) will never change, however the position of the person may move within an area of about 500mm radius in the centre of the room.

Would it be possible to set up a method of cancelling this noise out to be significantly reduced from the person in the centre of the rooms perspective? Does anyone have any understanding on how somebody would go about this?

Thanks in advance.

 

[jaedaliu]

Isolation is the easiest way. Put all the components in a different room, or put them in a box that vents to a different room.

 

[Barneel]

Isolation is the easiest way. Put all the components in a different room, or put them in a box that vents to a different room.

Hi Jaedaliu,

Thanks.. already attempted this, its currently in an enclosure lined with noise isolating foam. Unfortunately this causes the system to overheat, causing the fans to work harder and make more noise (damps the noise a little bit, but not enough for it to be worth over-working the fans).

I feel I have already attempted simple solutions. Budget is not a huge issue.

EDIT: Placing it in a separate room is currently not an option

 

[Harvey]

Active noise cancellation across the entire audio spectrum in all locations of an open room is mathmatically impossible. There are a number of acoustic isolation and noise reduction techniques, including floor, wall and ceiling treatments and acoustic baffles.

Many noise problems have as much to do with acoustic reflections, delays, cancellations and reinforcement at various frequencies as the noise sources, themselves. Under difficult conditions, understanding the problems and mplementing the necessary corrections requires someone with a good knowledge of acoustic measurements and a knowledge of these techniques and properties of the materials used to implement them.

For reference, I am an audio electronic design engineer. Every month, I meet with a group of audio professionals. When we moved to our new dining facility, the noise and echo problems were so bad that it was difficult to hold a conversation with someone standing next to you in a crowded room, and it was difficult to understand what speakers were saying during their technical presentations.

We immediately called on one of our resident noise reduction specialists to measure the room and, with the cooperation of the restraurant management, to build and place a series of aesthetically pleasing acoustic baffles that reduced the noise by around 20 dB and dramatically improved speech intelligibility. The baffles are all passive and relatively inexpensive, requiring no power other than that required to saw the boards used to construct them and the drills and screwdrivers required to assemble and hang them.

Since then, the owner of the restaurant has gone out of his way to thank us due to multiple compliments on the improvement in the entire environment from his other customers.

 

[Ayah]

painfully easy problem to solve, however it's all about the cash.

install air conditioning somewhere and just duct it in and out of the sealed equipment box.

or (works better if building is already set up for this like a solid state electronics/physics lab), outdoors insulated vacuum tank + liquid N2 and use that for cooling instead. way more problematic, precautions, legalities, etc. etc.

 

[Tech_Greek]

I've been tackling this problem my self after having clusters of servers that idle at 65-70 DB - the dell energy smart cabinets helped tremendously but didn't solve it.

I was able to get it down to 50-60 with the right placement of the equipment, distance from walls, etc. There has been a LOT of meticulous work involved - making a change and studying it to see the overall effect, I've literally spent hours staring at thermometers and DB meters while making slight changes every so often. 0_o

There are noise baffles, etc that you can buy but it's just as easy to make your own and that's what I'll be doing next.

 

[Barneel]

Thanks for all the advice everyone! I'm going to do a bit of research on your suggestions then come back!

 

[CycloWizard]

Anechoic chamber.

 

[DigDog]

the answer is: 1.you can't do it yourself. 2.it will be more expensive than what you can afford. 3.buying baffles and putting them casually around the room is not enough. 4.find another solution.

or hire a professional.

 

[Tsavo]

Get married.

It's the best way to learn how to tune out all annoying noises in your environs.

 

[oynaz]

Thanks for all the advice everyone! I'm going to do a bit of research on your suggestions then come back!

You should take Harvey's advice. Noise treating a room makes an incredible difference, and it is not that expensive. Even better, it is a one-off cost, since it is passive.

 

[Red Squirrel]

The solution is simple, make putting it in a separate room an option. If you have to, make that separate room part of that room. (partition wall). Is this a server rack, basically? Create a hot aisle and cold aisle isolated from each other. Then you only need to cool the cold aisle. You don't want to create an air pressure difference though, so essentially air from hot aisle needs to be able to eventually make it to the cold aisle.

I would just duct the cold aisle air from a cool location that has hvac ducts, then put the hot aisle air into hvac system. You may need to add AC into the equipment room. Actually if you do add AC you can just recirculate the air. Air from bottom of hot aisle ducted to top of cold aisle.

 

[Barneel]

The solution is simple, make putting it in a separate room an option. If you have to, make that separate room part of that room. (partition wall). Is this a server rack, basically? Create a hot aisle and cold aisle isolated from each other. Then you only need to cool the cold aisle. You don't want to create an air pressure difference though, so essentially air from hot aisle needs to be able to eventually make it to the cold aisle.

I would just duct the cold aisle air from a cool location that has hvac ducts, then put the hot aisle air into hvac system. You may need to add AC into the equipment room. Actually if you do add AC you can just recirculate the air. Air from bottom of hot aisle ducted to top of cold aisle.

Unfortunately this isn't easily possible... We have already sold several of these systems are were looking for more of an 'Upgrade' that has no effect on the current layout. Recirculating the air inside the enclosure using AC may be a possibility if we can find space for it inside the existing enclosure.

the answer is: 1.you can't do it yourself. 2.it will be more expensive than what you can afford. 3.buying baffles and putting them casually around the room is not enough. 4.find another solution.

or hire a professional.

2. It's only too expensive if we can't convince our clients to buy it...

Anechoic chamber.

+ Harveys response

We are researching how effective this would be


Thanks

 

[Carson Dyle]

The purpose of an anechoic chamber isn't to isolate the noise of what's in the chamber to the outside world, but to isolate the inside of the chamber from the noise of the outside world. So that you can measure how much noise the equipment in the chamber itself is producing.

The original questions seems a little divorced from the final goal. You manufacture some equipment that produces a disturbing, maybe even an unhealthy (probably a safe guess) amount of noise.

Is it not obvious that you have to put that equipment in some kind of enclosure that contains the noise, or else move it to a location away from human beings, so that they don't have to deal with the noise?

 

[Barneel]

The purpose of an anechoic chamber isn't to isolate the noise of what's in the chamber to the outside world, but to isolate the inside of the chamber from the noise of the outside world. So that you can measure how much noise the equipment in the chamber itself is producing.

When I said we are researching anechoic chambers I meant to see if we could use this inside the enclosure the equipment is contained within.

Is it not obvious that you have to put that equipment in some kind of enclosure that contains the noise, or else move it to a location away from human beings, so that they don't have to deal with the noise?

The purpose of this thread was to discuss alternatives. I am fully aware this would be the most effective solution, however this is not currently an option (and will never be an option as long as we are working with the design we have).


The noise isn't disturbingly loud... it's just mildly irritating as this system is designed to produce an immersive experience. I'm very appreciative of everyones interest and comments

 

[greenhawk]

depends on a few issues and as mentioned, it is not a easy task.

a cabinet and air conditioning on it can help a lot, but IIRC that depends on the frequency of the noise. Strength of the noise can be a issue as well at times.

The room itself can be adjusted in some ways by covering the wall so not a echo bouncing wall (and in a bad case, the right/wrong size to amplify a given harmonic).

Though the easiest is to look at the noise source itself and change it to be nicer. Say larger slower fans, bigger heat sinks (larger area) or working out if they are needed at all).

One I do prefer is substitution to a newer / better designed unit (depending on the gear).

though for best results, getting someone in who knows all about noise would be good. But if you are looking to sell this idea as a extra on the equipment, than some ideas will not work well as you will not know the finial installation location.

 

[greenhawk]

The purpose of this thread was to discuss alternatives. I am fully aware this would be the most effective solution, however this is not currently an option (and will never be an option as long as we are working with the design we have).

just what sort of noise? a low frequency one ? high pitch?

if a vibrating one, then a rebalancing of the source or a mounting system that does not bolt directly to the floor would be worth investigating.

 

[Barneel]

depends on a few issues and as mentioned, it is not a easy task.

a cabinet and air conditioning on it can help a lot, but IIRC that depends on the frequency of the noise. Strength of the noise can be a issue as well at times.

The room itself can be adjusted in some ways by covering the wall so not a echo bouncing wall (and in a bad case, the right/wrong size to amplify a given harmonic).

Though the easiest is to look at the noise source itself and change it to be nicer. Say larger slower fans, bigger heat sinks (larger area) or working out if they are needed at all).

One I do prefer is substitution to a newer / better designed unit (depending on the gear).

though for best results, getting someone in who knows all about noise would be good. But if you are looking to sell this idea as a extra on the equipment, than some ideas will not work well as you will not know the finial installation location.

Thanks, Greenhawk. I think our next course of action will be to get a professional in to take a look. Final installation location and details should not be an issue - we install the system ourselves and obtain building plans of the area we're installing into. Each system is customised to a degree to fit in with its surroundings anyway so variations of the solution are also an option as long as we can put a solid design-manufacture process in place.

just what sort of noise? a low frequency one ? high pitch?

if a vibrating one, then a rebalancing of the source or a mounting system that does not bolt directly to the floor would be worth investigating.

It's a low pitch noise - fans and servo drives mainly. The two big fans on the front are the main issue really. They make a lot of noise and also allow the noise of the components inside to leak out as well. In general its a fairly consistent noise, just varying in amplitude slightly when the drives are working hard.

 

[Biftheunderstudy]

Have you considered water cooling? That removes a lot of fan noise and means you can even relocate where the fans are to a certain extent (i.e. you could move them outside the room). And cuts off the component noise through the fan 'holes'. You would need to worry less about heat in the enclosure and could probably put in more sound insulation and baffles inside.

Depending on the heat load, passive heating via a large radiator could work or thermoelectric cooling.

Additionally, vibration isolation on the motors and servos.

 

[greenhawk]

The two big fans on the front are the main issue really. They make a lot of noise and also allow the noise of the components inside to leak out as well.

guessing the fans are not temperature controlled then to adjust as needed.

Though with a lot of fan/enclosure issues, I assume that there is a large enough opening at the bottom to allow air in? Failure on that will make fans sound different if they are effectivly creating a vacuum in the enclosure.

If the fans are a big part of the issue, can they be repositioned to the top / out of direct exposure to the operator? even on the top a hood can be used to keep dust out and deflect the hot air sideways.

 

[Barneel]

Have you considered water cooling? That removes a lot of fan noise and means you can even relocate where the fans are to a certain extent (i.e. you could move them outside the room). And cuts off the component noise through the fan 'holes'. You would need to worry less about heat in the enclosure and could probably put in more sound insulation and baffles inside.

Depending on the heat load, passive heating via a large radiator could work or thermoelectric cooling.

Additionally, vibration isolation on the motors and servos.

Water cooling is something that interests me - it's not something I have done before so it scares the hell outta me. Theres a big transformer at the bottom of the panel, if water were to drop on to that somehow.... :S

On a similar sort of note we have looked into air routing inside the enclosure - so that rather than just pumping cold air into the enclosure and cooling the whole thing, it gets routed directly to the heat-sinks on the drives to reduce waste in the hope that this would allow us to use a lower fan speed.

guessing the fans are not temperature controlled then to adjust as needed.

Though with a lot of fan/enclosure issues, I assume that there is a large enough opening at the bottom to allow air in? Failure on that will make fans sound different if they are effectivly creating a vacuum in the enclosure.

If the fans are a big part of the issue, can they be repositioned to the top / out of direct exposure to the operator? even on the top a hood can be used to keep dust out and deflect the hot air sideways.

The fans are temperature controlled, however we are in the process of replacing our current Rittal controller, as it often seems to have a mind of its own... We are currently unsure as to whether this is an issue with our set-up or the hardware/software itself...

We have vents on the roof (+ hood), and fans on the front of the panel. I'm sure creating a vacuum shouldn't be an issue, but perhaps we should do either a pressure check inside the enclosure or just remove the vents on the top temporarily to let plenty of air in and see if it makes a difference...


Thanks again for your responses!

 

[jaedaliu]

The fans are temperature controlled, however we are in the process of replacing our current Rittal controller, as it often seems to have a mind of its own... We are currently unsure as to whether this is an issue with our set-up or the hardware/software itself...

We have vents on the roof (+ hood), and fans on the front of the panel. I'm sure creating a vacuum shouldn't be an issue, but perhaps we should do either a pressure check inside the enclosure or just remove the vents on the top temporarily to let plenty of air in and see if it makes a difference...


Thanks again for your responses!

Industrial equipment isn't designed to be quiet. It's designed for filtering/isolation and air moving efficiency. Noise isn't important. What's your shop environment. With filters installed, are you able to prevent particles from entering the fan blades?

If so, consider switching your industrial fans & controllers for quieter PC fans. Make sure that they will provide enough air flow at low speeds. When you say "drives" I'm assuming you mean hard drives. Isolate those from the enclosure. Typically the hard drive clicks are noisiest when conducted through the walls of an enclosure. This can be done with simple rubber washers, or more complicated suspension devices.

Lastly, look at how air is exiting the enclosure. If you can direct it away so that it won't bounce towards the people working, that will reduce your perceived noise. Consider a dyson-like-no-buffet air baffle system to smooth out the air waves.

Really, one at a time, figure out what's causing the most noise, and quiet that. Repeat until happy.

 

[Barneel]

Industrial equipment isn't designed to be quiet. It's designed for filtering/isolation and air moving efficiency. Noise isn't important. What's your shop environment. With filters installed, are you able to prevent particles from entering the fan blades?

Hi Jaeduliu,

Noise is important in this situation. Minimal particles should be able to enter the fan blades, anything that gets close should be cut out by the filter - the room is also very clean.

If so, consider switching your industrial fans & controllers for quieter PC fans. Make sure that they will provide enough air flow at low speeds. When you say "drives" I'm assuming you mean hard drives. Isolate those from the enclosure. Typically the hard drive clicks are noisiest when conducted through the walls of an enclosure. This can be done with simple rubber washers, or more complicated suspension devices.

Unfortunately industrial fans (or something that can produce equal cooling) is really a requirement as these are high power servo drives that convert the kinetic energy produced by the rig (which is a lot) into heat energy that is dissipated into the system.

Lastly, look at how air is exiting the enclosure. If you can direct it away so that it won't bounce towards the people working, that will reduce your perceived noise. Consider a dyson-like-no-buffet air baffle system to smooth out the air waves.

Really, one at a time, figure out what's causing the most noise, and quiet that. Repeat until happy.

A dyson-like thing would be interesting to look into...

 

[Barneel]

Away for a week now so will reply to responses when I get back.....

 

[Ayah]

for watercooling, if the transformer is a worry, just encapsulate it or replace with a sealed unit or oil-immersed unit. (not sure of what "big" is)