Rule of thumb in acoustics is you need absorptive material that is as thick as 1/4 wavelength of the lowest frequency you are trying to absorb, e.g. 10mm of foam is only good for above 7kHz or so. The foam you have in the video seems far too thin, and also appears to not be an open-cell foam; Closed-cell foams mostly reflect sound, not absorb it. I think the first thing to try would be putting a block of sponge/polyester-fill in the 180degree turn and shortening the centre-panel(s) a bit to allow an air-gap where the sponge would otherwise impede the airflow around the bend.
@TheFreak111
9 ай бұрын
So for reducing voices which I find have wavelength about between 1 and 4 meters, I would need 0.25 to 1m thick layer? That is going to be near impossible for such a box.
@isaacharvey
9 ай бұрын
@@TheFreak111 For a ventilation 'acoustic maze' to be effective at damping LF then I suppose it would need to be longer to fit in longer sections of absorption at the bends. I'm not suggesting thick foam along the 'walls' of the maze, only foam at the bends to dampen reflections from continuing through the maze. The shortest path through the maze would also need to be of sufficient length to prevent long wavelengths from passing straight through it (unaffected by absorption); I'm not sure if the path length would need to be 1/4 wavelength or even longer like 1/2 wavelength. There may be other ways to dampen LF here, like the use of limp-mass diaphragms, but I'm not sure. As mentioned in the video, the maze will only help so much until more is done to prevent sound passing straight through walls and/or the door itself (solved by adding mass in walls/door), and any other air gaps like gaps around the door jamb and beneath the door (solved using seals). An acoustic 'maze' muffler/silencer would also inhibit ventilation via convection, so it could use a fan, as well as a second vent (possibly requiring a second maze) as an air intake/exhaust (depending on fan direction).
@TheFreak111
9 ай бұрын
@@isaacharvey ah ok so so I guess thicker at the bends would already be better? Could be done by shortening the path length, however that also needs to be long you mention. I found some 120 kg/m3 acoustic foam online that might be a good material and I'll give that a try. But at least now I know it won't be perfect and I should at a little more at the bends, tnx for sharing some knowledge.
@isaacharvey
9 ай бұрын
@@TheFreak111 yep thicker absorption at the bends, which will necessitate either making the entire box longer or reducing the lengths of the inner walls so that air can still flow freely. Note that I'm not an acoustician and this is only theoretical, though I know some fundamentals of acoustics from past audio experience and training.
@propositionjohnston
3 жыл бұрын
The sound clip you provided is like a side stick on a snare drum. And not particularly indicative of disturbing sounds from the next room it would’ve been better to do a spectral analysis or a pink noise sweep or something to see how it performs at different frequencies.
@laafawnduh
3 жыл бұрын
I think changing up the material might yield better results. More dampening foam. Good Idea though, im trying to solve the same issue with the same style vent above the door. I too think thicker doors would be the best solution but they are a much more expensive solution
@nicholasgott9393
2 жыл бұрын
I just did a three-panel maze for my transfer ducts using sound dampening felt instead of wood. I’m unfortunately now chasing the next weakest link which will is the doors and the gaps around the doors. The maze did lower the sound and it also had the effect of preventing any light from coming through the grille.
@Link8451
2 жыл бұрын
an easy fix for the door gaps is using weather stripping or some other type of door deal i put a rubber seal around the edges of my door and it worked wonders to reduce the noise coming in and out
@Patrick-vp4co
Ай бұрын
What kind of felt did you use?
@NormanStone3
3 жыл бұрын
Nice approach - but I think you can improve the materials & gap dimensions of the maze to reduce the sound.
@glenviewjeff
Жыл бұрын
I wonder how much air flow is restricted with the maze in place.
@robwalker5479
3 жыл бұрын
Thanks for the ideas!
@augusthuckabee6564
3 жыл бұрын
Your voice is so soothing my man
@PNWLiving1725
2 жыл бұрын
But did it work for sound in general?
@linzerpa
Жыл бұрын
I think a heavy sound absorbing material, like mass loaded vinyl sheeting, would work much better than that that light foam. It seems to absorb sound you need heavy material.
@johndierks9548
4 жыл бұрын
I'm curious if removing the foam from the ends of the 4 panel maze reduced it's performance compared to the 3 panel version you displayed?
@jvburnes
Жыл бұрын
You need open cell foam. I think you're using closed cell.
@TercesKun
4 жыл бұрын
nice video, thanks :D love your voice, and i think you could get the facial expression more appealing to the viewer :D
@TimGray
Жыл бұрын
You need to use tin carpet and not an acoustic reflective foam. would make a bigger difference.
@jackmorgan709
3 жыл бұрын
You won't do much better with a hollow core door, drywall, and no weather stripping or automatic door bottom! The vent was your weakest link, now it's something else.
@MrDeekaph
3 жыл бұрын
Nice experiment but your design is really flawed in the materials you used - that poly plastic will do nothing for absorption it will just echo the sound waves down the line. You really need to use batting or an acoustic material like sonopan.
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