Absorption Material

[Sencheezy 689]

As I begin my adventure in the SQ lanes, I have been doing a lot of research and studying. My general synopsis is, for SPL, in a vehicle, we want the most reflective material possible, such a concrete, or marble, so that there is no loss in energy. Obviously this is not practical, but in this example, it will work. Ok, and for SQ, we want the total opposite, we want complete absorption so that none of the higher frequencies reflect, which can cause interference, overlap, and many other issues. From what I've seen, things such as egg carts, foam, or MLV would be the fix. 

 

So what I am asking, what would be the best and most particle material to use in the vehicle for sound quality purposes? Particularly for the dashboard area to prevent reflection from the windshield. From what I've been told, one of the major goals is to get the sound stage to be perceived as front and center, (pointing at the center dash). But once you get the sound up there, there still may be some issues that needed to be ironed out due to sounds reflecting from the windshield. So I guess I'm asking what would be the best dampening material to address said issue? 

 

And again, this is all round 1 for me, so if my thinking thus far is flawed, please advise. 

 

As a side note, I've noticed the difference first hand. I was giving an demo to a good friend of mine, and he pointed out that I have too much reflection from the dashboard area. We placed a few of my heavy T-shirt/clothing on the dashboard, which is also made out of plastic, which is very reflective, and I immediately heard a sound difference. That sound difference, can anybody explain to me exactly what is going on here? Like, the science behind it or a good description.

 

I was taking a look at this particular site, under "absorption". http://whealy.com/acoustics/behaviour.html

[lithium 358]

you still have some misunderstanding of how it works. the material thickness has to be at least 1/4 the wavelength. so for sub bass you're not absorbing shit in a car. even up through the mid range there would very few surfaces where you could install inches of absorption material. 3m thinsulate works in the headliner because sound is traveling at angles other than perpendicular to the surface. 

 

to correct something you said, mlv is not an absorbed its a barrier. 

 

throwing shirts on the dash can only attenuate high frequencies. people use those carpet dash kits to accomplish the same thing. how much this helps probably depends on the location/aiming of the tweeter

Edited February 19, 2014 by lithium

[///M5 2,833]

Drive around in a fluffed marshmallow of multi-directional fibers and you are somewhat doing okay.

[Tenacious 32]

Fiberglass batting in a 1 mil plastic bag works well compared to most other materials. It's mostly useful for treating doors, though. It wouldn't be very pretty stuck all over panels in your vehicle.

 

A dashmat is the only product I can think of for helping problems with dash reflections. Your best bet would probably be aiming the drivers so that reflections are avoided in the first place.

[Sencheezy 689]

Fiberglass batting in a 1 mil plastic bag works well compared to most other materials. It's mostly useful for treating doors, though. It wouldn't be very pretty stuck all over panels in your vehicle.

 

A dashmat is the only product I can think of for helping problems with dash reflections. Your best bet would probably be aiming the drivers so that reflections are avoided in the first place.

 

Ok thanks, I will look into dashmat for my particular vehicle. 

[Sencheezy 689]

Drive around in a fluffed marshmallow of multi-directional fibers and you are somewhat doing okay.

 

 

lol

[///M5 2,833]

The largest semi-Anechoic chamber in the world is at a division of Cummins in a suburb of Minneapolis. You can use the room to measure down to about 30Hz. The room is long enough to park a semi in and has acoustic wedges that are around 8' long. There is also a false wall and bass trap behind them that is even bigger. I haven't been in the room in at least 9 months and didn't actually ask the size, just going from memory. Hopefully that explains the "marshmallow" comment a bit better.

Dash mats can help with high frequency reflections but are really rather horseshit as an absorption material.

[Sencheezy 689]

The largest semi-Anechoic chamber in the world is at a division of Cummins in a suburb of Minneapolis. You can use the room to measure down to about 30Hz. The room is long enough to park a semi in and has acoustic wedges that are around 8' long. There is also a false wall and bass trap behind them that is even bigger. I haven't been in the room in at least 9 months and didn't actually ask the size, just going from memory. Hopefully that explains the "marshmallow" comment a bit better.

Dash mats can help with high frequency reflections but are really rather horseshit as an absorption material.

 

Is there any other applicable products that can do a better job to help with high frequency reflections in a vehicle? 

[///M5 2,833]

You need space, hence my example from above.

Anechoic chambers look like this for a reason

[///M5 2,833]

Obviously that is a semi as it has a hard reflecting surface for a floor.

[Sencheezy 689]

whoa! haha. Now I can see what you mean. Hmmm, so essentially, there is no space in my vehicle to properly approach an effective method of reducing high frequency reflection?

[///M5 2,833]

I'd like to see you do the windshield

[SpeakerBoy 64]

I'd like to see you do the windshield

Welldamn.