electricalnoise reduction
My landlord replaced our fancy intercom system to a cheap one, I am guessing because of maintenance. The new one does not have any controls and I am trying to reduce the noise of the buzzing or, if possibly, replace it with a compatible one that allow for reducing the volume. The pics below show the model and the wiring:
In California for highways and busy streets they build sound walls, which are actually just brick brick walls. They use solid bricks, not hollow bricks, and the walls end up looking like this:
If you are a good arbitrator or debater, you might even make a good case to have the city, county or state build it for your neighborhood.
Another alternative is to use trees, shrub bushes or anything that can become a hedge in you yard. Even though the old golf saying is trees are 90% air but I've never hit one through a tree. the same words for noise. Hedges and trees will block noise too. Either case make sure you follow your local code on both the block and landscaping. Pull permits where necessary.
I guess you could try putting some thin foam or felt stick on pads on the inside of the door frame where the door contacts it. This should lower the sound of the wood to wood contact. If the knob hardware is also loud, try using some dry silicon spray lubricant on the moving parts and on the door hinges. Sleep well.....
Best Answer
The quick-and-dirty solution: place tape over the speaker grille. The 2" wide clear tape used for packaging/boxes provides a nice balance of muffling the sound while remaining visually unnoticeable on excessively loud childrens' toys; it'll probably do well here too.
The electrical solution: add some resistance to the speaker circuit. This could be done with a resistor added between the terminals right on the speaker, or with a resistor added in series with the speaker.
It's a bit hard to tell in the photo but I think I see the red wire from the speaker soldered to the top-left corner of the circuit board and a trace going from that point to the terminal marked 1. If that's correct then the easiest electrical hack is probably to disconnect the green wire and insert a resistor there.
The resistor could be a variable type ("potentiometer") like this 200 ohm Bourns 3386X-1-221LF
or it could be a through-hole fixed-value type that looks similar to this
The potentiometer is nice because you can adjust its resistance (and therefore the speaker volume) by turning the dial. You'll almost certainly have to solder wires to attach to those leads though. The through-hole resistor would be easy to install (no soldering) but you'll have to experiment to find the right value. Fortunately resistor kits with a variety of values can be had at low cost. Something in the range of 20-150 ohms will probably put the speaker volume where you'd like it.
If you find that this hack makes the voices in the intercom inaudible then you could add a momentary normally open push-button switch. The switch would be wired across the resistor so that when pushed the resistor is bypassed and the speaker goes to full/normal volume.