Often times residents know that there is a sound-leak in there room – but that is only the first step. Next, you need to pinpoint the sound leak in order to fix it. When trying to check where the sound is coming from, there are a number of rules of thumb to follow.
Just like inspecting a house prior to inspection, you should walk around all edges, and inspect all openings and passageways. Take your time to be sure you do not overlook any leaks. Also, limit your search to rooms that require better noise insulation – this will reduce the time needed to perform the soundproofing walk-down. Check in this order to determine where most of the noise can be eliminated.
Major Sources of Sound Leaks
Many doors are hollow-core, which allow significantly more sound to pass through. You can detect these by their lighter weight, and by knocking on them to hear whether they resonate (a solid-core door will sound “fuller”). Manufacturers make them like this to save weight and cost.
You can install a new composite or solid-core door, to reduce the noise passing through the door. You can also just add another layer onto the door, if you simply need to add mass and don’t mind damaging the existing door (AND don’t want to pay for a new one!). Check the gaps at the door threshold, especially in older homes. If the gap is significant, use a door sealing kit.
If you need to reduce noise passing through on a budget, or do not wish to make structural modifications, the AcoustiDoor is a good choice for you.
Is the window single-pane, double-pane, or a customized window? A second pane is instrumental in reducing noise transfer through the window, but this can often be offset by not having proper seals around the window. Check around the edges for any air flow, which may be repaired with caulk or re-sealed per the window specs.
If the issue is the glass being too thin, and allowing sound to pass through too easily, you can add a second pane with space in-between as a “deadened air space”. You can also add an acoustical curtain in front of the window to solve either issue – adding noise insulating mass, or shoring up leaks around the window’s edge.
3. Air ducts and returns
This is a common cause for sound leaking between rooms. Air ducts and returns are designed to optimize air flow through the residence, and as such, use large openings and unobstructed paths. Filters and grates will not diminish the sound transmission. Stand next to the opening, and listen for sounds that are distracting (is it the TV on in the other room, or the cars driving by outside?). You can also use an inexpensive decibel meter (I’ve used this one effectively, but make sure yours goes low enough to detect the sound bothering you – this one has a floor range of 30dBA).
Sometimes you can close these off manually, while other times you will need to order a custom curtain to see it off. Remember to leave at least one return open to allow airflow, and contact an HVAC or Acoustical Consultant if you do not want to modify it yourself.
4. Gaskets, Seals
The gaskets and seals around any of the fixtures in the wall, including those mentioned in this article, are designed to reduce the amount of noise passing through. However, some will break down over time, or were damaged during installation. Check the integrity of each seal with 2 tests.
First, and a personal favorite, is to perform a light test. Turn off all lights in the room and shield it from any incident light. Inspect the seal from the inside to determine if there is any light leaking through – if so, sound will be leaking through as well. Note: you can perform this test from the outside as well, by turning on internal lights and inspecting at night.
Second, you can use a paper test. Slide a piece of paper under the edge of the seal. If the seal is firm, it should hold itself up, and you should be able to dislodge it easily without having to pull hard.
When inspecting walls, check that they are completely interconnected, and no spaces are left between perpendicular walls. With a space of just an inch, it will sound like the conversation next door is happening within your same room. If there is a drop ceiling, remove a panel and ensure that the wall extends all the way to the next floor. The ceiling panels will not block any sound passing through.
If there is a gap in the walls, this allows what we call ‘flanking’ in the soundproofing industry. The sound will essentially circumvent the walls, and take the path of least resistance into the adjoining areas.
Take a brief walk around the perimeter of the walls, looking for small holes, and checking that there is a good seal at the floor. Check for air movement along the floor as a sign that it is not properly sealed (blowing dust, etc.). To perform a full check, you may need to pull back the trim and look for missing caulk. If you find that there are no holes or gaps, the issue may simply be a lack of sufficient mass in the wall. Adding an extra layer of soundblocking drywall, or reinforcing with bulk mass-loaded vinyl will significantly reduce the noise passing through.
6. Ceilings – concrete ceilings may share with the floor above
To pick low-hanging fruit, seal common openings, and patch any larger holes with heavy gypsum board – more layers is better, and always seal with caulk.
Be aware that concrete ceilings may share the same structure with the floor above, so noises will easily vibrate through them. If this is the case, you may need to hang an isolated ceiling with customizable hangers (typically neoprene) to create 2 truly separated surfaces. Likewise, you can create a floating floor if there is banging coming from below. Achieve this with neoprene or compressed glass fiber standoffs.
It is frustrating when there is noise getting into your room and you can’t find its source. It’s easy to do a quick walk-down and come up empty handed. That’s why finding sound leaks is a methodical process, and by following our proven approach, you’re assured to minimize your expenses and time in solving your soundproofing problems.