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Memory Foam frequency test Studio Monitors
Old 14th September 2011
Gear Nut

Memory Foam frequency test

I posted about finding a memory pad in another thread, but I thought I'd post the results of my testing in a new thread to make it easier for people to find.

First, these results are admittedly not scientific and I'm only regarding them as loose estimates. I'll tell you about my method and you can decide about the results for yourself.

I estimate the density of this stuff at about 4.25lbs/ft^3 and 4.5" thick. To test it, I set up a Yamaha HS50M and an AT4040 in my bathroom. My bathroom is about 10'x8' and has tile floors, a tile shower stall with glass doors, one 2 solid cement walls, a wood ceiling, and 2 wood walls. There are no wall coverings, one mirror, and one towel. I have a small bathmat by the shower. Next, I propped the foam up against the cement wall, using duct tape to hold it close and hold it up. I then pointed the speaker at it, and positioned the mic so that it was pointed at the foam at about an 80deg angle, slightly ajar from the direction of the speaker. The mic was about 16" away from the pad. I then routed the mic into logic, opened up a channel EQ and turned on the analyzer and muted the output (It still took in signal, but didn't send it out to avoid feedback loops). Lastly, I set up a second track with the Test Oscillator plug-in and ran through 10 frequencies. I then took down the foam and repeated the experiment.

I took screenshots of each frequency and then overlayed them all in photoshop. As you can see, there is some effect, if it is a little odd. First, you can see from 200-800hz there's definitely some reduction. There seems to be a pop around the 800-1.8khz range, and then the expected reduction in the high frequencies.

I do think this reduction is significant enough to warrant building absorbers out of this material, as that 200-800 range can create a lot of mud. I'm sure the pros will disagree, but oh well. I do what I want, haha.

The first graph is without the foam pad. The second graph is with the foam pad.
Attached Images
File Type: png without_pad.png (22.9 KB, 155 views) File Type: png with_pad.png (22.0 KB, 142 views)
Old 14th September 2011
Gear Nut

Oops, didn't realize PNGs don't show up. Here's some JPGs.
First is without foam pad, second is with it.
Attached Thumbnails
Memory Foam frequency test-without_pad.jpg   Memory Foam frequency test-with_pad.jpg  
Old 13th January 2012
Lives for gear
Originally Posted by seamus james View Post
Oops, didn't realize PNGs don't show up. Here's some JPGs.
First is without foam pad, second is with it.
Interesting. Just saw an ad in my local classifieds for queen sized memory foam pads for $49 bucks. Did you ever go further with this? Wondering if they'd be useful in a cloud panel over my drums or in a bass trap.

Also was thinking about really cheap futon sets: those student-stuffers (as we call them here) for college dorms can go really really cheap and comes with likely enough wood/slats to actually build 2, maybe 4 smaller panels out of it.
Old 14th January 2012
Lives for gear
amishsixstringe's Avatar

Man, I wouldn't go using that stuff all over the place, just because there was one little test that showed it touched 200Hz. Maybe the stuff is awesome, but me likey to see real data before actually applying it in a real setting (non testing-throwing money at a project for fun).

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