I have gone through a similar journey. In my case I believed the main problem was the neighbour next door. I got an extra layer of gypsum on the wall but turned out the noise comes from all sides. You can't win in such situation. Apartment buildings not built with noise isolation in mind should be illegal.
Had to move out and went to live on a house that was absolutely silent. Well, as long as no one outside was mowing the lawn or something.
Then, after 10 years, forgot the problem existed and decided to buy a new house near a busy road. What an idiot I am. Now going through all possibilities: already ordered an extra thick glass layer on my windows (it already has 3 layers), bought sound sound dampening panels (they do not do anything other than help a tiny amount with echo), sound dampening curtains (no effect, but at least stop the daylight well) and may even build a new fence and build glass walls around my balcony. But yeah, you can get used to traffic noise, I hear, and sound cancelling headphones solve the issue as long as I wear them (nearly all day anyway while I work)... it's getting better already after a couple of months. But stumping neighbours upstairs, your only defence really is headphones.
At high and medium frequencies, sound is like water. That means that a small gap can spoil the insulation. That's why recording studios are built as ‘boxes within boxes’.
Low frequencies require mass-spring systems in which the walls are decoupled.
Sound absorption panels don't do anything about insulation. They just condition the sound inside the room or make it less "echoy".
DIY Sound isolation is very, very difficult. If you want to do it, call an acoustic company that knows what they are doing. Not a generic construction company.
as sibling comment says, low frequencies are problematic. See what they put around highways, usually a 2cm thick glass and/or stone wall. Maybe put a good fence as far as possible from house?
But then there are even lower frequencies. They go through everything - they are shaking it.. thunder/rumble. A huge mass works, but i don't know if it's only way.
For example, find a hill/ridge that has the city on one side, and nothing/wilderness on other side, go on top of it. You will hear whole city - mostly low freqs. Go a bit further in the "nothingness" direction. Then a bit more. And listen.. the feeling is like your ears are being unplugged - it's that sound disappears - and you are so get used to it..
is noise from commercial aircraft low frequency? I live in DFW about 20min from a major airport and I remember going outside after 9/11 when all air traffic was grounded. It was eerily quiet even though I was still in the middle of a large metropolitan area.
Well it includes those low frequencies. I'm sure if you've flown you've experienced the strange ear-plugging feeling of flight. The fuselage is highly sound damped from the engines but you still get the low frequencies. Also could be that pretty much everyone tried to not go outside during 9/11, probably a lot more than just planes stopped
the air being pushed out/around from aircraft engines probably.
most running engines produce some low freqs, and also slow-rotational things.. like cars' wheels thumping on streets and roughnesses there.. esp. thousands of those. And then combinations of almost same freqs produce very low differentials - something on 50hz and another on 53hz will yield some 3hz. Which cannot be heard, it's to be felt.
Another similar silence happens if one is in a street/ suburb/ block-of-flats full of airconditioners-on-walls when the power goes off.
I don't think it's possible to build apartments or other connected houses in a way that isolates each unit from another, not without losing the efficiency / cost benefits of connected housing. Case in point, I live in a row of houses, but they just use long slabs of concrete for the flooring, creating a hard connection between the houses.
Mind you, it's fine (for me) most of the time, it's only really an issue if someone starts drilling / does anything in direct contact with the floors / walls.
There's really not much you can do short of building a room in a room. Your curtains and sound panels treat mid to high frequency but does nothing for the low frequencies of traffic that are penetrating your walls. You need a combination of mass and isolation to treat that.
Can you plant bushes or shrubs between you and the road? Also if you add a water feature between you and the road it would add more constant background noise which would raise the baseline that noises would have to exceed before you could hear them.
> Can you plant bushes or shrubs between you and the road?
A thin strip of foliage does (basically) nothing to reduce noise propagation. Dense foliage (meaning you can’t see anything through it or move through it) gets you about 1 dB reduction for every 10 feet of thickness.
one decibel reduction at what reference pressure, and for which frequencies? I think you don't really know, or you would have specified.
as with most things relating to acoustics, the truth appears to be extremely complicated[0] and foliage has different effects at different frequencies including reflection (which may perceived as amplification in some scenarios)
The implication is that we're talking about sound pressure level in air, therefore the reference pressure would be 20 µPa.
and for which frequencies?
Again, the implication is annoyance and in that context I'm looking at overall SPL in A-weighted decibels (A-weighted decibels, while not perfect, is reliably correlated with annoyance)
I think you don't really know
For the record I'm an expert [0] in acoustics and noise control. It's how I've made my living for the past 30 years. So yes, I really know.
or you would have specified
I wasn't trying to get into a detailed discussion here, but I'm happy to oblige for anyone that wants to learn.
as with most things relating to acoustics, the truth appears to be extremely complicated
Absolutely. That said, if you look at the link, the author mentions 8-9 dB of excess attenuation with 50 meters of intervening foliage. That correlates to about 1 dB of attenuation per 18 feet of foliage. Again, that demonstrates that a strip of foliage would do almost nothing to reduce sound levels. And for what it's worth, the phonemea the author is describing is not "absorption" - it's a combination of partial cancellation of the reflected/direct wave interaction in porous soil (same reason why snow covered ground makes things quieter) and refraction from leaves/trunks (which is why the foliage needs to be _dense_, otherwise soon waves travel through the gaps and provide no reduction).
[0] By "expert" I mean a) studied the subject as an undergrad at MIT b) worked for 30 years in the field, producing or contributing to several hundred Environmental Impact Statements in the USA, authoring/co-authoring a couple dozen papers and presentations including one peer-reviewed study, c) authored or contributed to acoustics guidance manuals for the U.S. Federal Transit Administration, Federal Aviation Administration and National Academies, d) have been admitted as an expert witness in acoustics/noise control in criminal and civil trials in seven states, e) have certification demonstrating noise control expertise [1], f) been recognized by my peers as having contributed to the field, g) have had research referenced by international researchers
My house is on the top of a hill. There is already some trees in front of it but it would be impossible to put several lines of them which would be needed to have any effect. I believe a good glass fence in front of the house will help a lot (together with the extra glass on the windows) by reflecting away most of the direct noise (but no idea if that will really work). I've already gone through lots of discussions about it, and you're right, a water feature is suggested often, I need to have a look at that.
