Sound deadening really necessary?

[jstan84]

Obviously sound deadening is important in my front doors where my components will be but the real question is will I see any real benefit to deadening the floors, walls, and rear doors?

I will only be running a front stage which will be kicker QS components, subs will be 2 type r 12s running on a kicker zx1500.1

The vehicle is a Nissan Titan crew cab, and it is already pretty quiet on the road. I dont really care about people being able to hear my truck rattling, all I care about is the sound inside. Will deadening the entire truck improve overall sound quality in the truck?

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[tylork92 10+ year member]

if your lookin for numbers it will help but if now just see how you like it without and then if theres too many rattles add some.

 

[SPLaudio 5,000+ posts]

will improve the sq no doubt. it dosent make you any louder just drowns out the tire,road and motor noise.

 

[audioholic 5,000+ posts]

Of the places you mentioned, the floor is the least important. It already has factory deadening and a healthy amount of carpet to soak up road noise.

 

[Rudy 10+ year member]

If you aren't worried about reducing noise from engine, tires/wheels and exhaust, the floor is out of consideration. Even if you are, as audioholic pointed out, resonance isn't a problem for the floor. You can pretty much jump straight to a barrier. We can eliminate increasing SPL as a goal because "sound deadening" (vibration damping, absorption, isolation and blocking) don't really help with that. That really leaves making your truck a better listening space. I consider reducing noise levels critical for that goal - thought I should say that //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

You are really left with two things to go after - panel resonance and rattles. Every panel in a vehicle has a resonant frequency or frequencies. That means the panel vibrates in response to some exciting energy and produces sound at that frequency or frequencies and harmonics of those frequencies - basically acting like a speaker producing a limited set of frequencies. Your sound system is an excellent source of energy since it produces sound over the entire audible range. Each panel in your vehicle will reinforce the frequencies at which it resonates. Vibration dampers control resonance.

The other issue is rattles. They make your vehicle sound like crap but they also create audible cues that are easy to localize. Subs are effective when they are behind us because the human ear can't localize the frequencies they play. Add a high frequency rattle in a panel near the sub and our attention is drawn to it. Same goes for mids, it's just not as obvious. Any attempt to reproduce music that doesn't draw attention to the hardware involved is foiled by rattles. R

attles are always two or more hard objects vibrating against each other. Vibration damper can help by reducing the energy available to drive the rattle but the best solution is to stop the objects from making contact. Tightening loose fasteners may be enough. Other times we need to put something in between the objects. A perfect example is foam between a trim panel and sheet metal.

 

[Second Skin]

Much like Rudy said,sound deadening doesn't help with SQ directly but it does quiet your listening space. the most important place to deaden for road noise is actually the doors. the floor is usally optional. the doors are so important because the sounds from the tires on the road travels strait up through the frame and bounces around in the hollow spaces in the doors, kind of like a drum. after that like Rudy said your main issue is going to be any places you're hearing rattles.

AX

 

[genxx 10+ year member]

****, look samething different day. Let Don answer the question then just agree.

Don is 100% right, I agree 100%, just like Don said 100%.LMAO

SS so the sound travels from my tires into my door bounces around in a hollow space making sound. Now I just put deadener on my door the sound goes in the still hollow space and is now absorbed by the alum. backing or is still bouncing around, the sound wave that is. To achieve what you suggest would you not have to fill the entire hollow space or some how seal it from cab to trap the sound.

It works well in the floor to help get rid of tactile feel in a comp. vehicle. Other than that no reason to do the floor in a daily driver. I have one comp. veh. with the floor done and one not. It has not effect the scoring in any way shap or form.

 

[Rudy 10+ year member]

Much like Rudy said,sound deadening doesn't help with SQ directly but it does quiet your listening space. the most important place to deaden for road noise is actually the doors. the floor is usally optional. the doors are so important because the sounds from the tires on the road travels strait up through the frame and bounces around in the hollow spaces in the doors, kind of like a drum. after that like Rudy said your main issue is going to be any places you're hearing rattles.
AX

Deadening, used interchangeably with vibration damping, plays a relatively small part in attenuating air borne noise. It is an important foundational step. The OP specifically said he wasn't interested in reducing noise intrusion. My comments were in response to his specific objective and should not be taken as a general purpose solution to every problem. Applying a barrier to the floor would have been my first suggestion if mitigating road noise had been an important goal for him. I think I actually said that. Even for that application, supplemental vibration damping on the floor plays a very limited role.

The majority of tire noise is air borne. Even if some of the sound found its way into the "hollow spaces in the doors", the bulk of it travels up and through the floor. It can be reflected off other vehicles or obstacles along the road and enter through the doors that way, but doors are a secondary concern for engine, tire/wheel and exhaust noise. There are other excellent reasons to treat the doors.

I pretty much said the opposite of what you have attributed to me. Vibration dampers help a lot with music reproduction by minimizing the contribution from panel resonance. What they aren't very effective at is quieting the listening space, at least when it comes to noise sources that originate outside of the passenger compartment. You need a barrier for that. It's very important to identify the issue and then apply the appropriate solution.

 

[Lakota 5,000+ posts]

I totally disagree that sound deadener can't help SPL. The Termlab knows all.

 

[audioholic 5,000+ posts]

I totally disagree that sound deadener can't help SPL. The Termlab knows all.

The TL has shown improvements in SPL from deadening, and its shown no help or even losing db's. Ive concluded there is no definitive answer to how it will affect your SPL score when speaking in such general terms as we are here.

 

[Rudy 10+ year member]

I totally disagree that sound deadener can't help SPL. The Termlab knows all.

Two things happen when you apply a constrained layer damper:

1. Vibration is converted to heat - SPL declines
   
2. The panel is reinforced slightly, SPL goes up
   

These are largely offsetting and it's almost impossible to predict which will dominate. To maximize SPL, reinforce the panel without vibration damping - panel distortion steals energy that could otherwise be metered.

 

[audioholic 5,000+ posts]

Stiffening a panel will increase SPL. Deadening the panel (damping it) may or may not increase SPL.

For stiffening a panel, think internal bracing (just like your enclosure), or using products like fiberglass to reduce panel resonance without adding the visceolastic effect of converting sound wave energy into heat.

 

[roarzorz 10+ year member]

Deadening the cab floor in my Explorer (older model) had the greatest effect on quieting road noise. It was like driving a different vehicle with a noticeably audible difference. I didn't notice any difference when doing the doors, roof, or hatch area.

 

[Lakota 5,000+ posts]

Deadening also changes the resonance of the vehicle. My resonance frequency has changed from the deadener that I put in my truck. Stiffening panels doesn't always help. If I brace certain parts of my truck (make them stiffer) I LOSE score.

 

[audioholic 5,000+ posts]

With all the reflecting surfaces in a vehicle, and the fact that the cabin does not pressurize evenly throughout (and the SPL mic is place in only one portion of the cabin), there are always exceptions. But generally speaking, when the goal is increasing air pressure (sound pressure), keeping the 'container' as close to its original shape as possible will help your SPL.

With that said, *sometimes* flapping panels help a score by simply adding to the 'noise', assuming its resonating within the frequency band being measured.