That gap on top of this post is intentional. Air Gaps are your friend when it comes to soundproofing!
Every band dreams of practicing freely in a room without neighbours dropping in with a scowl on their faces. Similarly, every studio hopes to record the most subtle aspects of music without worrying about the surrounding urban noise. These two places need soundproofing for opposite reasons – jamming rooms must prevent sound from going out, and studios need to prevent sound from coming in.
This post discusses the soundproofing requirements of jamming rooms, and lists some loopholes to watch out for. Soundproofing for studios requires a separate post.
Jamming Rooms generate noise levels equivalent to around 100-110 Db – close to twice or thrice the loudness you hear at a noisy traffic signal. This can get distressing because by definition, practice implies long hours. Involuntary listening for long hours can get disturbing – leading to annoyance, irritation, headaches, raised heart rates, and raised blood pressure. A sustained elevated heart rate is good for a workout – staying in such a state for long causes a dip in your longevity.
How much soundproofing do these rooms need?
The good news is, there’s no need to have a zero output concept here. Urban noise is expected to be at least 60 db during daytime, and around 43 db during night time in residential areas. What’s even better news, our ears perceive loudness logarithmically, and so the decibel scale is logarithmic. That means if you reduce the sound even by 10dB, you perceive it as only half as loud.
Soundproofing projects are always more challenging than those which require acoustical treatment for reverberation, or fine tuning. This is because heavy mass is needed to block sound, and most venues do not afford space. A room within a room is the best option, but when that’s not possible due to structural constraints (or in the absence of permission to make structural changes to a building), alternatives must be carefully calculated.
The common mistake here is that while gypboard constructions can be used for isolation, the calculations must be for that purpose alone. Expecting gypboard configurations that work for absorption, to also work for isolation, is a folly here – one that I see all too often around me. Rockwool or glasswool will do nothing to absorb sound at low frequencies if you don’t stop them first.
A word of caution to DIY guys.
- All soundproofing materials come with numbers that tell you how much transmission loss they give. Do not assume that simple arithmetic will give you accurate results. The materials come with a clever line “All joints to be properly sealed and caulked”. Here lies the whole game.
- Also, the materials are tested under lab conditions – the numbers will vary rather widely under different site conditions.
- Further, they come with instructions on how to construct. If structural constraints or budget force you to make variations, discuss them with an acoustical consultant, not the vendor.
- While heavy absorption helps in transmission loss if carefully designed, careless use of absorption materials will make your drum kit sound dead. A drum kit produces a wide range of frequencies – 50 to 15kHz. The high frequencies will sound dead almost immediately, while low frequencies will painfully linger on if you provide too much absorption in the room.
The other important thing to watch out for are leakages due to site constraints, or plain human error. Every soundproofing project has a leakage fixing phase. A 1 mm gap is enough to turn a 99 % success into a 100 % failure. Also, the most important thing to watch out for is leakages due to structural contacts. You may come up with a clever design, but if you drive nails or screws through to hold things together, that’s a short circuit route. Acoustical caulks must be carefully chosen. I know carpenters who use metal paste to block leaks. It’s rather difficult to convince them of the structural coupling it provides.
Lastly, a note about budgeting. Soundproofing materials are more expensive than absorption materials. All choices must be based on calculations, with generous discounts on the claimed performance, keeping site conditions in mind. While budget constraints are understandable, it is vital to have a talk with an acoustical consultant to understand what part of it can be DIY, and what part of it must be professionally installed.
The funny part is, road traffic noise can be a blessing for such projects. I have two precisely opposite cases on hand – one project next to a noisy road, and one located in a quiet residential layout. Needless to say, the sound reduction needed in the latter was huge, and with structural changes not being an option, I had many sleepless nights reading quoted transmission loss numbers and separating the grain from the chaff.
If there’s a choice of location, try to choose a noisy location, so that you don’t stand out. Low frequencies and structural vibrations are the toughest to isolate, but there are clear laws defining how things work, so in the right hands, your project can be a decent success even with budget constraints. Happy Jamming!
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