How can I reduce the propagation of noise inside a home?

Question

How can I reduce the propagation of noise inside a home?

I have an apartment that's about 85 m2, with three bedrooms, 2 bathrooms, plus living room and kitchen. If anyone eats cereal in the kitchen, I can clearly hear the slightest clanging of the spoon against the plate all the way in the master bedroom, which is the farthest away from the kitchen. It's driving me insane.

I want to prevent noise in general from propagating so much from one place to another.

I've been looking into acoustic panels, but all the DIY videos and blog posts I've seen so far are about using them to isolate a studio. I'm not looking for absolute isolation, but rather for a way that I can place them in key places to reduce the noise. I have no clue of what types of panels to use or how to figure out what the key places would be. Any pointers on this particular would be especially useful.

I should also try to use something that is not too aesthetically displeasing, so as to not incur the rage of my wife ;) Preferably something that almost looks like decoration. Perhaps like this.

I've also been looking into special rugs that can absorb noise or acoustic paint.

Also, we have central air conditioning, so I think the fake ceiling and the ducts may be amplifying the noise. I read something about placing "noise traps" inside the ducts. Building a sort of zigzag of barriers or half-boxes using acoustic panels.

Questions:

• Looking at the plans I've shared above, what key places should I place acoustic panels in?
• Would acoustic paint for the living room and hallway to the rooms help?
• Would a rug in the hallway to the rooms help?
• Would "noise traps" in the ducts for the air conditioning be a good idea?
• Anything else I should consider?

Answer 1

In principle you can reduce the amount of sound travel by

• sound absorbers placed against reflecting surfaces along the path of the noise, e.g. carpets, draperies and other objects specifically designed for sound absorption
• heavy obstructing objects positioned in the path that noise travels, such as weighted doors, double thick walls, thick ceilings and floors
• restricting apertures along the path, e.g. by keeping windows, doors, vents small or closed etc...

As suggested in the comments, you should first examine your situation closely to determine how the noise travels.

Often sound travels by multiple paths, e.g. through a wall, as well as around a hallway, and through small openings around wall switches and receptacles.

Our ear cannot always tell which dominates if there are such multiple paths. It is a well known phenomenon that we determine the direction (or source) of a sound mostly by its high frequency components, even if the sound's energy at high frequencies is much less than at lower frequencies.

Putting it in practical terms: sometimes it's not easy or obvious to determine how noise travels and where to do something about it. So much for your challenge. You may think that hanging the kitchen door back should take care of the noise, not realizing there is a high frequency component traveling under the door or through ducts, and that makes muffled sounds through walls appear stronger and more irritating.

If you are willing to put the time and effort into thorough investigations, you will be rewarded with an effective result because it will be specifically tailored to your problem and therefore it does not have to be unsightly or unwifely.

Your first step should be to find out what the source of the sound is, and where it originates. I think you have it pegged to yoghurt at 3am in the kitchen. But perhaps you are also concerned with foot drop noise, even if it is on the same floor.

Next you need to find out how that specific sound travels, and one way -as wisely suggested in the comments- is to block and test.

Block all possible paths you can think of, by hanging doors, blocking doors with thick materials (panels, blankets, mattresses), stuffing vents with pillows etc... This is an experiment, not a solution, so it's ok to briefly plug holes that otherwise serve important ventilation. Plug everything until the noise is no longer heard.

Be reasonable; you will not deaden all sound travel, so perhaps you could just play some music softly in the kitchen, from a loudspeaker placed on the table. After each passage blocked, determine your success. There are free spectral sound measurement tools available for your phone, so you could use those, or just make a subjective observation and give it a number between 0 and 5.

Sometimes it helps to move your test noise source closer to a door, wall or vent etc... to see if that makes it appear louder in the bedroom, thus highlighting the specific way noise exits the kitchen.

And now comes the trick: noise transmission is reciprocal. You can determine how it enters the bedroom by reversing the noise travel direction. Place the speaker at different locations in the bedroom (near door, wall, vent etc...), and record your observations when listening in the kitchen.

When you return with your results, we can tackle the biggest contributor first and propose some ways to mitigate.