Making on board generator quieter

Wolfpack Fan · 10-09-2011, 01:47 PM

A lot of you are probably already aware of this neat little trick. We did some tailgating with our motorhome this weekend at our University. Not sure where I'd heard about it, but supposedly putting a carpeted mat of some sort directly beneath the generator quiets it down. Makes sense because a lot of the mechanical sound from the generator bounces off of the hard pavement.

Well I tried it and it surely does work.

mustang652 · 10-09-2011, 02:48 PM

Reduces both primary and secondary noise as you are traping air under the unit and dampening vibration.

TXiceman · 10-09-2011, 03:02 PM

Quote:

Originally Posted by mustang652

Reduces both primary and secondary noise as you are trapping air under the unit and dampening vibration.

How is the air trapped? The carpet is on the pavement and the normal air flow is not disturbed. The carpet acts as a sound deadener and absorbs some of the sound and not letting it reflect off the pavement.

ken

Wolfpack Fan · 10-09-2011, 03:06 PM

I might try something a little different next weekend tailgating. I can get my hands on a rubber mat with holes in it. Like the one's typically found behind bars or in commercial kitchesn. I'll put that on top of the carpeted mat. Should work a little better. Now I just need to finish up my homemade gen turi project.

mustang652 · 10-09-2011, 03:27 PM

Quote:

Originally Posted by TXiceman

How is the air trapped? The carpet is on the pavement and the normal air flow is not disturbed. The carpet acts as a sound deadener and absorbs some of the sound and not letting it reflect off the pavement.ken

All of the above.

Well, not being a sound and/or vibration engineer I reckon trapping is not the best term to use, but the carpet keeps all the air from being forced out between the ground and the base, therin reducing the flow of sound by that travels from the unit to the ground.

LadyFitz... · 10-09-2011, 03:36 PM

Quote:

Originally Posted by mustang652

All of the above.

Well, not being a sound and/or vibration engineer I reckon trapping is not the best term to use, but the carpet keeps all the air from being forced out between the ground and the base, therin reducing the flow of sound by that travels from the unit to the ground.

The Iceman had it right. There is no air flow involved soundwise.

JayGee · 10-09-2011, 03:53 PM

Thanks for the tip. It makes sense that it might slow down the sound bounce. I'll try it!

C-PHartley · 10-09-2011, 04:47 PM

If you are experimenting, try an accordion style fold of the carpet to absorb or dampen the noise. I did some acoustic work in a shopping center once and was amazed at how much noise a flat surface reflected as opposed to an irregular surface.

TXiceman · 10-09-2011, 06:01 PM

Any soft textured surface will help to absorb sound. Have you ever seen the inside of an anechoic chamber. All of the walls are covered with wedges of a fiber mesh about 1.5' deep (tall) on all of the walls, floor and ceiling. The operating surface is a wire mesh suspended near mid height in the chamber. The walls a thick concrete, lead lined and the whole room floats on an air bag system.

As noted above, it is not the air that is the problem as sound travels in waves. High frequency and low frequency sounds are treated in different ways. Sound travels in straight lines and it is readily reflected by hard surfaces.

Place a high nap carpet under the generator set that extends 2 or 3 feet past the generator on all four sides.

I Have done some work on low noise equipment in quiet areas and it is a very specialized field and not a simple field.

Ken

Ramblin · 10-09-2011, 06:20 PM

Sound is air PRESSURE variation, expressed as waves. The number of times the air pressure cycles from its lowest point to its highest point per second is its frequency. Sound deadening techniques focus on stopping the PROPEGATION of these air pressure variations through absorbsion or diffusion or both. That's what the rug is doing under the genny.

EDIT: After re-reading this, I realized it would be an excellent reply to the DW asking "What is MY RUG doing under the GENNY?!?"