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If anyone has further useful information please post it here. Please Do not bring arguments about which brand is best based on only you having used it once or twice. Only results showing db reductions, STC, or similar measured reductions of sound are wanted here.
Reason for this thread
I looked at soundproofing my truck because of the engine noise. I turned the radio off on almost a 2,000 mile trip because it was to loud in the cab for me to enjoy the music while driving down the road.
At idle my sound meter says I have 85 db sitting still. I am really only hearing the knock of the engine itself. Most often people spend a lot of time and money putting on the various sound deadeners over the entire inside of their trucks. After tearing out the interior they put the aluminum foil backed sticky stuff over almost every inch of the interior. Is that however the best approach?
Most of the information I found regarding soundproofing said brand A is better, no brand B is, then brand C is mentioned as being best... Then the arguments continue with nothing to back up any claims made. I still have seen very little to show that most automotive sound proofing material actually stops any sound. I keep hoping to find the scientific approach. This material has a STC of (insert number here) at 125 hz (diesels have low frequency sound) so I could compare and determine which material should work best for my use.
What frequencies do we need to be concerned with to quiet a diesel engine?
Low Frequency Noise Concerns
" The audible frequency range varies from about 20 Hz (hertz, or cycles per second) to about 20,000 Hz. An example of a low-frequency source is a large idling diesel engine, which can produce large amounts of low-frequency sound in the range from 20 Hz to 150 Hz. Low-frequency sounds (long wavelengths) tend to travel easily over long distances. Therefore, it is most efficient to control low-frequency noise at the source, although it may be difficult to obtain a satisfactory result."
This is why we have so much trouble quieting a diesel engine. It produces low frequency sounds. Because of their nature they are hard to block out. The same situations exists when you hear a car playing music way to loud. 1/2 mile away you only hear the bass because the higher frequency sounds naturally dissipate over that distance.
You will find that sound proofing materials get tested over several different frequencies. Some materials work best at those frequencies that will not affect the noise of our diesels enough to notice.
Why are the newer diesels quieter?
We have learned that the new diesels inject fuel 3 distinct times instead of once like our older trucks do. Those multiple injections produce lower emissions and less noise. There are other improvements we can add to our trucks to reduce the noise levels our trucks produce also.
<from Noise reduction effort update - Page 3 >
"The really quiet Mercedes diesels are the ones that intrigue me. I used to work for DaimlerChrylser before the 'Diamler Debacle' ended my career with them. I had the opportunity to speak with a couple of their engineers and ask how they made their diesel engines so quiet.
This is what I was told, I haven't been able to verify it all, but it makes sense:
Double wall valve covers, double wall exhaust manifold shields, and double wall exhaust pipes are used to a great extent. The injectors, injector lines, and injection pump is either buried or shielded wherever possible."
Look under the hood of the new trucks. There is a lot of soundproofing under the hoods today. You will even see soundproofing on the inner fenders. That has to be there to stop noise from getting into the cab instead of helping people outside of the truck who think it is to loud. If you can put enough soundproofing on, under, and around the engine and engine components including the turbo, injection pump, and exhaust pipe that will greatly reduce the noise coming into the cab from the engine.
Areas of our trucks producing or transmitting sound
A lot of sound comes through the windshield and other windows. Except for closing the windows and making sure the seals are intact there is nothing we can do to stop sound from these sources.
The back wall has nothing to block sound. If you have loud exhaust soundproofing the back wall is a good plan.
The floor will transmit sound especially from the exhaust sitting underneath it.
The firewall transmits engine sound quite nicely.
A lot of noise comes out of the valve cover.
The injection pump is just plain noisy.
A lot of sound comes through the doors.
The roof can be a culprit largely due to vibration when you have drone coming from stacks.
Tires can create a lot of noise depending on the tread pattern.
Wind and other road noise. This can be a result of worn out seals or mounts.
The exhaust can make a lot of noise especially when modified.
The oil pan on the cummins 5.9 in our trucks resonates like an empty 55 gallon oil drum.
One person used a DB meter and said the oil pan is the noisiest place on the engine. It is about 110 decibels at one foot!! Years ago the government Dept Of Labor said 1/2 hour a day was all that was allowed for exposure to that level of sound.
Exhaust pipe modification for quieter running From Lsfarms
"What I did for my downpipe is to take a length of 4" straight pipe and slit it lengthwise and open it up like a big 'C' then slip it over the straight sections of the down pipe, then tack-weld it in place such that there was an 1/8" gap between the inner pipe and the new outer 'skin'. Then I wrapped the whole thing with the fiberglass header-wrap. It seemed to help."
There are some heavy duty trucks that come factory with double walled exhaust pipe. Maybe this is a good sound solution most of us miss.
Drone
One person had the dreaded drone with one exhaust setup and eliminated it by changed the preload and hanger locations to stop the pipe from resonating and droning.
Clamp a piece of angle iron onto the straight pipe to change its weight and resonance to reduce and eliminate drone. Putting different lengths and weights may be required to find the sweet spot.
(from) TheDieselStop.Com Forums: Can I dampen my drone? Please!
"Do a search on "flex kits" and you may find your answer. My truck had a significant drone/resonance starting in the 1700 RPM range. After reading a couple of positive posts about installing a section of flexible exhaust I obtained a pre-made kit that consists of a 6" section of flex exhaust complete with the couplers and U bolts. I installed the kit last night and I am very pleased with the results. I cannot hear/feel the drone." (and) "The flex pipe eliminates about one third of the normal noise this truck makes" That makes sense as putting in a flexible pipe would change the resonance frequency of the exhaust system.
Another person glued lead sheet using liquid nails panel adhesive onto their roof. This was done because of drone using stacks. That helped the drone a lot. The roof can be a cause for excess noise in at least some cases.
Stock trucks are around 92-98 Db under load at 70 mph. (88-90db is where most say hearing damage starts) and this is more than enough to cause hearing damage over time.
Those folks who have drone at 2000-2200 rpm are in the 96-98 Db range. If you have to turn your radio way up to hear it on the highway, then turn the radio way down at a stop light the truck needs some sound proofing.
(Tire and road noise)
Obviously this has 2 solutions.
1. Put on quieter tires.
2. Soundproof the cab.
3. Use earplugs while driving. This is not really a proper solution but will help to prevent hearing damage.
The tires chosen can make a vehicle a lot quieter or noisier.
Product types (not brand names) to consider using
There are 3 ways to reduce sound through sound proofing
1 absorb = foams
2 change resonance = any panel stiffener (my imperfect terminology)
3 block sound = lead or mass loaded vinyl (transfers sound wave into heat)
When it comes to sound deadening there are typically three types of products used, mass loaders, FLDs, and CLDs.
(from here) peel and seal as sound deadning - Page 3 - Product Reviews - Post a review on a product you have first hand, personal experience with. - SMD Forum
Mass loaders are exactly what they sound like, they add mass to lower the resonance frequency of the panel. Asphalt based products typically fall into this category because they lack the viscoelastic properties that the butyl products do.
Mass loading was a popular technique in years past, but mass loading is EXTREMELY ineffective. Why? You need to apply approximately four times the weight of the panel to drop the panels resonance just one octave. I don't know about you, but I don't want 100 pound doors just to listen to my music clearly.
The other two types of products are CLDs (constrained layer dampers) and FLDs (free-layer dampers).
CLDs include Dynamat, Damplifier, Audio Wrap, SDS Tiles, etc.
Simply put, CLDs convert the vibrational energy into low level negligible heat. The reason P&S ISN'T an effective or efficient CLD is the fact it doesn't have a thick enough constraining layer (foil) to do any good.
FLDs include products like Spectrum, LizardSkin, Cascade VB-1X, etc. There are FLDs that are not liquid, but these are the most common ones in our field.
The way FLDs work is that vibrational energy is dissipated as a result of extension and compression of the damping material, vs. a cld where the energy is lost through shear deformation of the material.
Typically speaking CLDs have the upper hand over FLDs because of their ability to maintain a higher loss factor across a wider range of frequencies, temperatures, and thicknesses of the substrate. Basically they are more efficient at controlling vibrations. This is especially true when applications require a light weight solution. For instance on a substrate of say 1/8", a cld mat of only 1/16" may be required to control the vibrations. The FLD on the other hand may require three or four times the thickness, so 3/16 to 1/4", to achieve the same loss factor.
P&S simply lacks the properties that would make in an effective vibration control product. It's not heavy enough to make a difference (unless you slap on 50+ pounds of the stuff). It doesn't have a thick enough constraining layer to withstand the shear strain of panel flex. It has a poor adhesive (typically consisting of asphalt, bitumen, petroleum distillates, and/or low grade rubber).
I've said it once and I'll say it again, DO NOT USE PEEL AND SEAL!
(from here) TheSamba.com :: View topic - Sound deadening comparison video: Read this thread. It has a lot of useful information beyond what is quoted below.
"There are three categories of sound deadening/vibration control products out there, and unfortunately most people don't know the difference.
First you have mass loaders. This is old technology and is fairly ineffective at reducing vibrational energy and resonance.
These products are typically constructed from asphalt or asphalt and rubberized compounds and weigh a significant amount.
They work by adding mass to the panel to lower the panels resonance frequency. Only issue is that you have to quadruple the weight of the panel to drop one octave. A skin of a door weighing three pounds would need nine pounds of material added to it to see a reduction of only one octave. So by the time you achieve a noticeable reduction in sound, you would have 70-80 pound doors.
Then you have CLD (constrained layer dampers). These products are lighter weight and sport a butyl based adhesive, no asphalt. They should have a fairly thick constraint layer (typically an aluminum one) as the correlation between the thickness of the aluminum layer and the effectiveness of the product go hand in hand. These products work by converting the vibrational energy into low level negligible heat.
And finally you have FLDs (free-layer dampers), or extensional dampers. These would include most liquid vibration products and a few self sticking mat products. The way they work is that vibrational energy is dissipated as a result of extension and compression of the damping material, vs. a cld where the energy is lost through shear deformation of the material.
Typically speaking CLDs have the upper hand over FLDs because of their ability to maintain a higher loss factor across a wider range of frequencies, temperatures, and thicknesses of the substrate. Basically they are more efficient at controlling vibrations. This is especially true when applications require a light weight solution. For instance on a substrate of say 1/8", a cld mat of only 1/16" may be required to control the vibrations. The FLD on the other hand may require three or four times the thickness, so 3/16 to 1/4", to achieve the same loss factor.
Once a panel is sufficiently 'dead' by using a CLD or FLD product, other means of blocking and absorbing sounds are needed.
CCF (closed cell foam) rarely, if ever, adds much of anything to providing a quieter ride. It's best used as a decoupler to 'float' a MLV layer above the surface or as a gasketing material to prevent rattles and squeaks. So anyone who suggests you use CCF to increase your sound deadening results is just trying to get more $$$ from you."
Peel and stick dampers are designed to control and reduce vibrations, not block sound. These products are just too thin and lightweight to block sound.
MLV (and thin lead) on the other is designed to block sound because of it's thickness and mass. Average noise loss when using a 1 pound per square foot MLV is around 25 dBs (across a wide range of frequencies). So the addition of a MLV over a vibration mat would just further decrease the noise level inside the vehicle, creating a much more pleasant listening environment. And remember, MLV has been used in the building industry for years as a barrier without a foam decoupler. Sandwiched between the 2x4s and sheetrock MLV creates an amazing sound barrier between rooms, great for isolating media/theater rooms and even apartments.
As stated several times in the industry, 25% coverage is pretty much all that is needed to sufficiently control vibrations. Upping that to 50% coverage may only increase the results a decibel or two, probably not enough for most anyone to notice.
How to apply sound deadening products for best results
Read this thread. It appears to cover almost everything you wish to know about applying soundproofing. Sound Deadening 101 - Diesel Place : Chevrolet and GMC Diesel Truck Forums
Firewall and sound deadening material - Page 2 - Ford Powerstroke Diesel Forum
" I am an acoustical engineer (certified) B.S.E.E. San Diego State, and MECP (Mobile electronics certification Program) Master installation technician. And many of you have it all wrong?!?! Dyna mat and such (asphalt base dampening materials) are not for blocking sound from entering the cab although they will "if there is 100% coverage" it is too cost prohibitive considering the much better and much less costly alternatives! the dyno-mat and such was designed to be used as a material to stop the "RINGING AFFECT" of the metal sheet itself (Known as resonant frequency dampening) and should be used in center of flatter areas at or larger than a square ft or so in patches of around 4" ( Must be applied to clean dry surface and heated to get good adhesion) Test application, example thump the area of sheet metal firewall etc w/finger nail and you will hear a tink then again after application and you will hear a thud!!! patches should be placed evenly on inside and motor side of firewall to cover and eliminate higher pitched "Noise" then a shredded treated automotive insulation should be used to dampen lower frequencies usually in 1/2 in thick (looks like a carpet pad made of shredded multiple colored string "available usually at HOME DEPOT 5 ft wide and by the linear ft! C H E A P ! " attach pad w/spray glue "3M heavy duty or equiv." use this inside cab only as it will absorb and retain moisture as high and as full of coverage as you can on firewall and I also recommend another layer under the whole cab carpet "If you have a floor shift insulate with this here too as well as possible this treatment will make your truck sound like a lexus on hwy!!!!!!! OK not, but you should be able to reduce internal noise w/windows closed by at least 10 - 25 decibels = MAJOR IMPROVEMENT!!! "
Is there a big difference from dynomat to something like peel n' seal? - Page 3 - Car Audio Classifieds
there are a few tutorials out there for proper placement of sound deadening but it's really not all that necessary if you follow two simple rules.
1. Only 25% of a panel needs to be treated. So a door that measures 6 sq. ft. should theoretically need no more than 1.5 sq. ft. of actual sound deadener (not Peel & Seal).
2. Placement of the material should be in the center most of the panel. No need to treat reinforced or welded areas, just the flattest areas of panels need it. Now why only 25% coverage you may ask? That tends to be the best bang for your buck in terms of achieving great results.
For instance, 50% panel coverage will typically increase the sound lose 2-3 decibels over 25% coverage. And 100% coverage will net another 2-3 decibels over 50% coverage. So the overall sound loss difference between 25% coverage and 100% coverage is typically 4-6 decibels. Quite often it's less than that.
Also when you just go all out and go 100% coverage, you (the typical person) tend to cover up and treat areas that do not need it, thus wasting product, time, and most importantly... money.
(That means there is some benefit to complete coverage but may not be worth spending that much more money.)
Solutions
Once I read that someone put something over the engine oil pan and valve covers with the result of greatly reduced the engine noise it made sense to me. I talked to a diesel injection pump rebuilder. I was told just the p-7100 injection pump alone sounds like a diesel truck running when it is being tested on the bench. To me that means put sound insulation around the injection pump also. If the injection pump is so loud other parts of the engine could also be noisy and need quieting down.
This is one website showing a product they sell that they claim kills off a lot of engine noise. It is a very expensive approach. I am sure something similar could be made at home.
DodgeRam
Here is a report by a person who bought and installed that kit.
Installed ATP Wap Noise reduction kit - Dodge Diesel - Diesel Truck Resource Forums
"Tim used a db meter to check the sound, with the kit intalled he said it read 59db at idle." Although I am not sure where the db meter was placed that is a huge reduction in sound from what I have now at 85db in the cab.
These 2 threads are long. Look at the sound reduction from making a lead liner around the oil pan. Also, notice that the first pan cover fell off while driving down the interstate. A better mounting system was needed and used the second time.
Noise reduction effort update (and)
Noise Reduction
Pay attention to Lsfarm's replies.
"I got 2 sheets of lead put in and the cab is back in order.
The sound test came in at +- 2-1/2 db less than before on the low end and hardly any change at the top end of the frequency scale. The tester said that is a 75% drop in noise and according to him most of the noise drop is in the lower levels area."
"I covered the oil pan, and changed the sound of a screwdriver tapping on the side of the pan from a "ting, ting" sound to a "thunk, thunk" sound.
The unprotected pan radiated sound at 102dB!! With the layer of lead, it radiated at 92-93dB. then I put my pan blanket back on and the pan now reads 90dB. All these readings in my shop on a concrete floor.
Wheelwell readings went from 96-98 db down to 87-89dB."
"Open your hood, and look between the fender and the hood hinge down inside just ahead of the door hinges. There is a thin 1/4" foam 'seal' just ahead of the door hinges. I added a layer of the 'superfoam' from GSI over the top of the factory piece. There is a lot of noise coming into the cab from this area."
"I had chimed in earlier when I had covered the firewall and cowl area. At that point, I had a baseline noise reading of 84 to 86 dbA on the center console between seats. The firewall work brought noise down to 81 or so at my baseline freeway speed of 82 mph. I completed seat removal and followed Greg's experience and covered all the areas outlined in his threads. The results are too amazing to have not done this a long time ago. I now have readings of 74 to 75 dbA which is more than 10 points lower than at the start. My main culprit was reflected engine and road noise. I now hear the engine sound as it should be but no overwhelming other noises. The truck is now much more pleasant to drive and I'm sure will result in less fatigue on the long hauls."
"I found the area around the steering column to be a big transmitter of noise. There is an aluminum casting supporting the steering column on the inside of the cab, and bare metal on the engine side of the casting, so there is nothing insulating this area so it picks up and radiates all the noise from the engine right into your lap.
I just cut pieces of foam to fit around the braces and brackets, cut slots in the foam to go around wiring. A bit of trim adhesive will hold the foam in place.
Use some foam around the floor shift if you have one. The floor of the cab radiates a lot of road and exhaust pipe noise.
Some panel deadener on the floor was effective in my truck"
One person laid some lead sheet across the entire firewall and across the top piece that the top of the dash screws into. Doing the firewall made a big difference even with the rest of the truck already done.
If after putting some sound barriers over the oil pan, valve covers, and injection pump there is still more noise than you want I would put soundproofing material on both sides of the firewall and on the inner fenders. Look at your under hood firewall insulation. Some later trucks have a panel that comes all the way up to the hood. Also, later trucks had an insulator that more or less covers the bell housing and transmission. Go to a dealership. Look under the hood of the new trucks. There is a lot of soundproofing under the hoods today. Add the same kind of sound proofing to an old truck and you should get some sound reduction.
It may be true that soundproofing the cab is mostly a waste of time for most who do not have drone. Maybe soundproofing the engine is where the effort and money should be concentrated. After all, most of us are not looking at a super expensive sound system trying to eliminate panel rattle. We are not trying to kill off most of the road and wind noise. We are trying to silence the mighty cummins engine noise for a more comfortable ride.
http://powerstrokenation.com/forums/showthread.php?t=62831
The noise reduction measurement of Lizard Skin applied to valve covers looks like a 1-2 dB difference.
A comparison video
Here is a long video showing several different brands of soundproofing subjected to heat. If whatever you buy slides down and then off the panel it is not what you want in your vehicles.
https://www.youtube.com/watch?v=XWBzhEUG-LI
Reason for this thread
I looked at soundproofing my truck because of the engine noise. I turned the radio off on almost a 2,000 mile trip because it was to loud in the cab for me to enjoy the music while driving down the road.
At idle my sound meter says I have 85 db sitting still. I am really only hearing the knock of the engine itself. Most often people spend a lot of time and money putting on the various sound deadeners over the entire inside of their trucks. After tearing out the interior they put the aluminum foil backed sticky stuff over almost every inch of the interior. Is that however the best approach?
Most of the information I found regarding soundproofing said brand A is better, no brand B is, then brand C is mentioned as being best... Then the arguments continue with nothing to back up any claims made. I still have seen very little to show that most automotive sound proofing material actually stops any sound. I keep hoping to find the scientific approach. This material has a STC of (insert number here) at 125 hz (diesels have low frequency sound) so I could compare and determine which material should work best for my use.
What frequencies do we need to be concerned with to quiet a diesel engine?
Low Frequency Noise Concerns
" The audible frequency range varies from about 20 Hz (hertz, or cycles per second) to about 20,000 Hz. An example of a low-frequency source is a large idling diesel engine, which can produce large amounts of low-frequency sound in the range from 20 Hz to 150 Hz. Low-frequency sounds (long wavelengths) tend to travel easily over long distances. Therefore, it is most efficient to control low-frequency noise at the source, although it may be difficult to obtain a satisfactory result."
This is why we have so much trouble quieting a diesel engine. It produces low frequency sounds. Because of their nature they are hard to block out. The same situations exists when you hear a car playing music way to loud. 1/2 mile away you only hear the bass because the higher frequency sounds naturally dissipate over that distance.
You will find that sound proofing materials get tested over several different frequencies. Some materials work best at those frequencies that will not affect the noise of our diesels enough to notice.
Why are the newer diesels quieter?
We have learned that the new diesels inject fuel 3 distinct times instead of once like our older trucks do. Those multiple injections produce lower emissions and less noise. There are other improvements we can add to our trucks to reduce the noise levels our trucks produce also.
<from Noise reduction effort update - Page 3 >
"The really quiet Mercedes diesels are the ones that intrigue me. I used to work for DaimlerChrylser before the 'Diamler Debacle' ended my career with them. I had the opportunity to speak with a couple of their engineers and ask how they made their diesel engines so quiet.
This is what I was told, I haven't been able to verify it all, but it makes sense:
Double wall valve covers, double wall exhaust manifold shields, and double wall exhaust pipes are used to a great extent. The injectors, injector lines, and injection pump is either buried or shielded wherever possible."
Look under the hood of the new trucks. There is a lot of soundproofing under the hoods today. You will even see soundproofing on the inner fenders. That has to be there to stop noise from getting into the cab instead of helping people outside of the truck who think it is to loud. If you can put enough soundproofing on, under, and around the engine and engine components including the turbo, injection pump, and exhaust pipe that will greatly reduce the noise coming into the cab from the engine.
Areas of our trucks producing or transmitting sound
A lot of sound comes through the windshield and other windows. Except for closing the windows and making sure the seals are intact there is nothing we can do to stop sound from these sources.
The back wall has nothing to block sound. If you have loud exhaust soundproofing the back wall is a good plan.
The floor will transmit sound especially from the exhaust sitting underneath it.
The firewall transmits engine sound quite nicely.
A lot of noise comes out of the valve cover.
The injection pump is just plain noisy.
A lot of sound comes through the doors.
The roof can be a culprit largely due to vibration when you have drone coming from stacks.
Tires can create a lot of noise depending on the tread pattern.
Wind and other road noise. This can be a result of worn out seals or mounts.
The exhaust can make a lot of noise especially when modified.
The oil pan on the cummins 5.9 in our trucks resonates like an empty 55 gallon oil drum.
One person used a DB meter and said the oil pan is the noisiest place on the engine. It is about 110 decibels at one foot!! Years ago the government Dept Of Labor said 1/2 hour a day was all that was allowed for exposure to that level of sound.
Exhaust pipe modification for quieter running From Lsfarms
"What I did for my downpipe is to take a length of 4" straight pipe and slit it lengthwise and open it up like a big 'C' then slip it over the straight sections of the down pipe, then tack-weld it in place such that there was an 1/8" gap between the inner pipe and the new outer 'skin'. Then I wrapped the whole thing with the fiberglass header-wrap. It seemed to help."
There are some heavy duty trucks that come factory with double walled exhaust pipe. Maybe this is a good sound solution most of us miss.
Drone
One person had the dreaded drone with one exhaust setup and eliminated it by changed the preload and hanger locations to stop the pipe from resonating and droning.
Clamp a piece of angle iron onto the straight pipe to change its weight and resonance to reduce and eliminate drone. Putting different lengths and weights may be required to find the sweet spot.
(from) TheDieselStop.Com Forums: Can I dampen my drone? Please!
"Do a search on "flex kits" and you may find your answer. My truck had a significant drone/resonance starting in the 1700 RPM range. After reading a couple of positive posts about installing a section of flexible exhaust I obtained a pre-made kit that consists of a 6" section of flex exhaust complete with the couplers and U bolts. I installed the kit last night and I am very pleased with the results. I cannot hear/feel the drone." (and) "The flex pipe eliminates about one third of the normal noise this truck makes" That makes sense as putting in a flexible pipe would change the resonance frequency of the exhaust system.
Another person glued lead sheet using liquid nails panel adhesive onto their roof. This was done because of drone using stacks. That helped the drone a lot. The roof can be a cause for excess noise in at least some cases.
Stock trucks are around 92-98 Db under load at 70 mph. (88-90db is where most say hearing damage starts) and this is more than enough to cause hearing damage over time.
Those folks who have drone at 2000-2200 rpm are in the 96-98 Db range. If you have to turn your radio way up to hear it on the highway, then turn the radio way down at a stop light the truck needs some sound proofing.
(Tire and road noise)
Obviously this has 2 solutions.
1. Put on quieter tires.
2. Soundproof the cab.
3. Use earplugs while driving. This is not really a proper solution but will help to prevent hearing damage.
The tires chosen can make a vehicle a lot quieter or noisier.
Product types (not brand names) to consider using
There are 3 ways to reduce sound through sound proofing
1 absorb = foams
2 change resonance = any panel stiffener (my imperfect terminology)
3 block sound = lead or mass loaded vinyl (transfers sound wave into heat)
When it comes to sound deadening there are typically three types of products used, mass loaders, FLDs, and CLDs.
(from here) peel and seal as sound deadning - Page 3 - Product Reviews - Post a review on a product you have first hand, personal experience with. - SMD Forum
Mass loaders are exactly what they sound like, they add mass to lower the resonance frequency of the panel. Asphalt based products typically fall into this category because they lack the viscoelastic properties that the butyl products do.
Mass loading was a popular technique in years past, but mass loading is EXTREMELY ineffective. Why? You need to apply approximately four times the weight of the panel to drop the panels resonance just one octave. I don't know about you, but I don't want 100 pound doors just to listen to my music clearly.
The other two types of products are CLDs (constrained layer dampers) and FLDs (free-layer dampers).
CLDs include Dynamat, Damplifier, Audio Wrap, SDS Tiles, etc.
Simply put, CLDs convert the vibrational energy into low level negligible heat. The reason P&S ISN'T an effective or efficient CLD is the fact it doesn't have a thick enough constraining layer (foil) to do any good.
FLDs include products like Spectrum, LizardSkin, Cascade VB-1X, etc. There are FLDs that are not liquid, but these are the most common ones in our field.
The way FLDs work is that vibrational energy is dissipated as a result of extension and compression of the damping material, vs. a cld where the energy is lost through shear deformation of the material.
Typically speaking CLDs have the upper hand over FLDs because of their ability to maintain a higher loss factor across a wider range of frequencies, temperatures, and thicknesses of the substrate. Basically they are more efficient at controlling vibrations. This is especially true when applications require a light weight solution. For instance on a substrate of say 1/8", a cld mat of only 1/16" may be required to control the vibrations. The FLD on the other hand may require three or four times the thickness, so 3/16 to 1/4", to achieve the same loss factor.
P&S simply lacks the properties that would make in an effective vibration control product. It's not heavy enough to make a difference (unless you slap on 50+ pounds of the stuff). It doesn't have a thick enough constraining layer to withstand the shear strain of panel flex. It has a poor adhesive (typically consisting of asphalt, bitumen, petroleum distillates, and/or low grade rubber).
I've said it once and I'll say it again, DO NOT USE PEEL AND SEAL!
(from here) TheSamba.com :: View topic - Sound deadening comparison video: Read this thread. It has a lot of useful information beyond what is quoted below.
"There are three categories of sound deadening/vibration control products out there, and unfortunately most people don't know the difference.
First you have mass loaders. This is old technology and is fairly ineffective at reducing vibrational energy and resonance.
These products are typically constructed from asphalt or asphalt and rubberized compounds and weigh a significant amount.
They work by adding mass to the panel to lower the panels resonance frequency. Only issue is that you have to quadruple the weight of the panel to drop one octave. A skin of a door weighing three pounds would need nine pounds of material added to it to see a reduction of only one octave. So by the time you achieve a noticeable reduction in sound, you would have 70-80 pound doors.
Then you have CLD (constrained layer dampers). These products are lighter weight and sport a butyl based adhesive, no asphalt. They should have a fairly thick constraint layer (typically an aluminum one) as the correlation between the thickness of the aluminum layer and the effectiveness of the product go hand in hand. These products work by converting the vibrational energy into low level negligible heat.
And finally you have FLDs (free-layer dampers), or extensional dampers. These would include most liquid vibration products and a few self sticking mat products. The way they work is that vibrational energy is dissipated as a result of extension and compression of the damping material, vs. a cld where the energy is lost through shear deformation of the material.
Typically speaking CLDs have the upper hand over FLDs because of their ability to maintain a higher loss factor across a wider range of frequencies, temperatures, and thicknesses of the substrate. Basically they are more efficient at controlling vibrations. This is especially true when applications require a light weight solution. For instance on a substrate of say 1/8", a cld mat of only 1/16" may be required to control the vibrations. The FLD on the other hand may require three or four times the thickness, so 3/16 to 1/4", to achieve the same loss factor.
Once a panel is sufficiently 'dead' by using a CLD or FLD product, other means of blocking and absorbing sounds are needed.
CCF (closed cell foam) rarely, if ever, adds much of anything to providing a quieter ride. It's best used as a decoupler to 'float' a MLV layer above the surface or as a gasketing material to prevent rattles and squeaks. So anyone who suggests you use CCF to increase your sound deadening results is just trying to get more $$$ from you."
Peel and stick dampers are designed to control and reduce vibrations, not block sound. These products are just too thin and lightweight to block sound.
MLV (and thin lead) on the other is designed to block sound because of it's thickness and mass. Average noise loss when using a 1 pound per square foot MLV is around 25 dBs (across a wide range of frequencies). So the addition of a MLV over a vibration mat would just further decrease the noise level inside the vehicle, creating a much more pleasant listening environment. And remember, MLV has been used in the building industry for years as a barrier without a foam decoupler. Sandwiched between the 2x4s and sheetrock MLV creates an amazing sound barrier between rooms, great for isolating media/theater rooms and even apartments.
As stated several times in the industry, 25% coverage is pretty much all that is needed to sufficiently control vibrations. Upping that to 50% coverage may only increase the results a decibel or two, probably not enough for most anyone to notice.
How to apply sound deadening products for best results
Read this thread. It appears to cover almost everything you wish to know about applying soundproofing. Sound Deadening 101 - Diesel Place : Chevrolet and GMC Diesel Truck Forums
Firewall and sound deadening material - Page 2 - Ford Powerstroke Diesel Forum
" I am an acoustical engineer (certified) B.S.E.E. San Diego State, and MECP (Mobile electronics certification Program) Master installation technician. And many of you have it all wrong?!?! Dyna mat and such (asphalt base dampening materials) are not for blocking sound from entering the cab although they will "if there is 100% coverage" it is too cost prohibitive considering the much better and much less costly alternatives! the dyno-mat and such was designed to be used as a material to stop the "RINGING AFFECT" of the metal sheet itself (Known as resonant frequency dampening) and should be used in center of flatter areas at or larger than a square ft or so in patches of around 4" ( Must be applied to clean dry surface and heated to get good adhesion) Test application, example thump the area of sheet metal firewall etc w/finger nail and you will hear a tink then again after application and you will hear a thud!!! patches should be placed evenly on inside and motor side of firewall to cover and eliminate higher pitched "Noise" then a shredded treated automotive insulation should be used to dampen lower frequencies usually in 1/2 in thick (looks like a carpet pad made of shredded multiple colored string "available usually at HOME DEPOT 5 ft wide and by the linear ft! C H E A P ! " attach pad w/spray glue "3M heavy duty or equiv." use this inside cab only as it will absorb and retain moisture as high and as full of coverage as you can on firewall and I also recommend another layer under the whole cab carpet "If you have a floor shift insulate with this here too as well as possible this treatment will make your truck sound like a lexus on hwy!!!!!!! OK not, but you should be able to reduce internal noise w/windows closed by at least 10 - 25 decibels = MAJOR IMPROVEMENT!!! "
Is there a big difference from dynomat to something like peel n' seal? - Page 3 - Car Audio Classifieds
there are a few tutorials out there for proper placement of sound deadening but it's really not all that necessary if you follow two simple rules.
1. Only 25% of a panel needs to be treated. So a door that measures 6 sq. ft. should theoretically need no more than 1.5 sq. ft. of actual sound deadener (not Peel & Seal).
2. Placement of the material should be in the center most of the panel. No need to treat reinforced or welded areas, just the flattest areas of panels need it. Now why only 25% coverage you may ask? That tends to be the best bang for your buck in terms of achieving great results.
For instance, 50% panel coverage will typically increase the sound lose 2-3 decibels over 25% coverage. And 100% coverage will net another 2-3 decibels over 50% coverage. So the overall sound loss difference between 25% coverage and 100% coverage is typically 4-6 decibels. Quite often it's less than that.
Also when you just go all out and go 100% coverage, you (the typical person) tend to cover up and treat areas that do not need it, thus wasting product, time, and most importantly... money.
(That means there is some benefit to complete coverage but may not be worth spending that much more money.)
Solutions
Once I read that someone put something over the engine oil pan and valve covers with the result of greatly reduced the engine noise it made sense to me. I talked to a diesel injection pump rebuilder. I was told just the p-7100 injection pump alone sounds like a diesel truck running when it is being tested on the bench. To me that means put sound insulation around the injection pump also. If the injection pump is so loud other parts of the engine could also be noisy and need quieting down.
This is one website showing a product they sell that they claim kills off a lot of engine noise. It is a very expensive approach. I am sure something similar could be made at home.
DodgeRam
Here is a report by a person who bought and installed that kit.
Installed ATP Wap Noise reduction kit - Dodge Diesel - Diesel Truck Resource Forums
"Tim used a db meter to check the sound, with the kit intalled he said it read 59db at idle." Although I am not sure where the db meter was placed that is a huge reduction in sound from what I have now at 85db in the cab.
These 2 threads are long. Look at the sound reduction from making a lead liner around the oil pan. Also, notice that the first pan cover fell off while driving down the interstate. A better mounting system was needed and used the second time.
Noise reduction effort update (and)
Noise Reduction
Pay attention to Lsfarm's replies.
"I got 2 sheets of lead put in and the cab is back in order.
The sound test came in at +- 2-1/2 db less than before on the low end and hardly any change at the top end of the frequency scale. The tester said that is a 75% drop in noise and according to him most of the noise drop is in the lower levels area."
"I covered the oil pan, and changed the sound of a screwdriver tapping on the side of the pan from a "ting, ting" sound to a "thunk, thunk" sound.
The unprotected pan radiated sound at 102dB!! With the layer of lead, it radiated at 92-93dB. then I put my pan blanket back on and the pan now reads 90dB. All these readings in my shop on a concrete floor.
Wheelwell readings went from 96-98 db down to 87-89dB."
"Open your hood, and look between the fender and the hood hinge down inside just ahead of the door hinges. There is a thin 1/4" foam 'seal' just ahead of the door hinges. I added a layer of the 'superfoam' from GSI over the top of the factory piece. There is a lot of noise coming into the cab from this area."
"I had chimed in earlier when I had covered the firewall and cowl area. At that point, I had a baseline noise reading of 84 to 86 dbA on the center console between seats. The firewall work brought noise down to 81 or so at my baseline freeway speed of 82 mph. I completed seat removal and followed Greg's experience and covered all the areas outlined in his threads. The results are too amazing to have not done this a long time ago. I now have readings of 74 to 75 dbA which is more than 10 points lower than at the start. My main culprit was reflected engine and road noise. I now hear the engine sound as it should be but no overwhelming other noises. The truck is now much more pleasant to drive and I'm sure will result in less fatigue on the long hauls."
"I found the area around the steering column to be a big transmitter of noise. There is an aluminum casting supporting the steering column on the inside of the cab, and bare metal on the engine side of the casting, so there is nothing insulating this area so it picks up and radiates all the noise from the engine right into your lap.
I just cut pieces of foam to fit around the braces and brackets, cut slots in the foam to go around wiring. A bit of trim adhesive will hold the foam in place.
Use some foam around the floor shift if you have one. The floor of the cab radiates a lot of road and exhaust pipe noise.
Some panel deadener on the floor was effective in my truck"
One person laid some lead sheet across the entire firewall and across the top piece that the top of the dash screws into. Doing the firewall made a big difference even with the rest of the truck already done.
If after putting some sound barriers over the oil pan, valve covers, and injection pump there is still more noise than you want I would put soundproofing material on both sides of the firewall and on the inner fenders. Look at your under hood firewall insulation. Some later trucks have a panel that comes all the way up to the hood. Also, later trucks had an insulator that more or less covers the bell housing and transmission. Go to a dealership. Look under the hood of the new trucks. There is a lot of soundproofing under the hoods today. Add the same kind of sound proofing to an old truck and you should get some sound reduction.
It may be true that soundproofing the cab is mostly a waste of time for most who do not have drone. Maybe soundproofing the engine is where the effort and money should be concentrated. After all, most of us are not looking at a super expensive sound system trying to eliminate panel rattle. We are not trying to kill off most of the road and wind noise. We are trying to silence the mighty cummins engine noise for a more comfortable ride.
http://powerstrokenation.com/forums/showthread.php?t=62831
The noise reduction measurement of Lizard Skin applied to valve covers looks like a 1-2 dB difference.
A comparison video
Here is a long video showing several different brands of soundproofing subjected to heat. If whatever you buy slides down and then off the panel it is not what you want in your vehicles.
https://www.youtube.com/watch?v=XWBzhEUG-LI
