Acoustically sound: Why you should soundproof your space
Dealing with excessive noise is the unfortunate reality for most households in Dhaka, regardless of how upscale a neighbourhood one lives in or works at
Soundproofing your space in Dhaka might seem like an unattainable luxury for many, but the adverse health effects through constant exposure to unwanted noise does not discriminate — its impacts on everyone's body and mind are undeniable.
Dealing with excessive sound, which you could call just 'noise', is the unfortunate reality for most households in Dhaka, regardless of how upscale a neighbourhood one lives in or works at.
In layman's terms, 'acoustics' is the science of sound. Primarily, acoustics deal with the properties or qualities of a room or building, which determine how sound is transmitted in it. And that is exactly what we need to have a rudimentary understanding of if we are to manage unwanted sound in our spaces.
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Health impacts and the ground reality of Dhaka
The negative health impacts of living in an environment that exposes us to excessive noise is somewhat difficult to comprehend. The impacts can never be readily felt or seen; they accumulate over time.
"We never act on it because we don't even see the demerits," says architect Jannatul Ferdous.
She recounts the decline of her father's health after working in a printing press for over 30 years, highlighting that such workplaces have extremely poor acoustic environments. This exposure led to her father's early hearing loss and Parkinson's disease.
Furthermore, noise pollution can affect various other aspects of life, from disrupting sleep to impairing concentration and relaxation. Even the analog clock on your wall ticking away can have a detrimental effect on your health.
A long-term study by the US National Center for Biotechnology Information (NCBI) reveals that increased exposure to vehicle noise and related air pollution can raise the risk of developing type-2 diabetes. Statistics show that 10% of people with hearing impairment are exposed to unwanted noise levels.
Noise exposure can also lead to heart disease, high blood pressure, and stroke, often without the individual realising it, due to constant annoyance and sleep disturbances.
What is soundproofing?
Before exploring soundproofing materials, it is important to understand the difference between sound absorption and soundproofing. Many people mistakenly believe they are the same, but sound absorption is just one aspect of soundproofing.
Sound absorption serves two primary functions: as part of a soundproofing system within structures like stud walls to prevent reverberation, and on surfaces such as walls or ceilings to reduce resonance and improve room acoustics — a process known as acoustic calibration. For instance, sound-absorbing panels in noisy restaurants can balance the internal acoustics.
Soundproofing, on the other hand, involves preventing sound waves from entering or leaving a room.
This is achieved through several key principles.
Deflection involves adding mass and density to structures, like concrete or dense boards, to block sound waves, especially effective against airborne sounds like voices or music from speakers.
Absorption uses insulating materials to soak up acoustic energy and prevent resonance in cavities.
Decoupling reduces direct mechanical linkage between structures and finishing materials, interrupting sound vibrations through techniques like counter battening or using resilient channels and acoustic brackets.
Thermal conversion employs materials which convert sound energy into trace heat energy, reducing flanking transmissions. This method enhances acoustic performance despite its subtle thickness.
Constrained layer damping uses specific materials in particular ratios to reduce resonant frequencies and flanking transmissions, effective for low-frequency noises. Damping compounds between rigid panels convert sound to heat through friction.
Combining these principles — deflection, absorption, decoupling, thermal conversion, and constrained layer damping — yields the best soundproofing results, each complementing the others to create an effective acoustic isolation strategy.
The caveat when it comes to finding these materials in Bangladesh is the lack of centralised stores — there is no specific shop out there specialised in dealing with insulation or sound absorbing materials.
"You'll find a handful of stores in your Banani and Baridhara areas but you may discover those stores are specialised in selling other materials, such as glass, etc. Honestly, there's no alternative to seeking expert guidance from your designated architect when you're looking for acoustic materials," said architect Nazia Afsoon.
How to soundproof your space
The architects we consulted strongly believe that the primary step in soundproofing a space is to identify sound sources and mitigate their impact.
"It's not about eliminating external noise, but about managing it," said Jannatul Ferdous.
Nazia Afsoon, an expert in outdoor acoustics, emphasised that proper acoustic analysis should be conducted during the building's design phase. This involves monitoring the space and surrounding streets, identifying sound sources, and using deflective or reflective materials to control the sound and prevent it from entering your area.
"We also consider future conditions. For instance, your building might have an open field in front now, but in five years, there could be construction in that space. We account for such possibilities and plan accordingly," added Nazia.
Indoor acoustics, though, present a different challenge.
Jannatul, who specialises in indoor acoustics, advocates for running software analyses before any acoustic design. However, this can significantly increase costs, which leads some clients to forgo the analysis phase.
"Without the software analysis, an acoustic design could still cost around Tk1.5-2 lakh. Honestly, if someone's asking us to run an acoustic refurbishment on a 10,000 sq ft apartment, adding Tk500 per sq ft is enough to provide for the entire soundproofing cost," said Jannatul.
A simpler method for mitigating indoor noise is rearranging existing furniture or designing a new furniture layout that absorbs external noise to keep it below harmful decibel levels.
Medically, the ideal sound level in our homes should be around 60 decibels. However, in Dhaka, almost every house experiences sound levels between 80 and 90 decibels.
Another crucial aspect often overlooked in Dhaka is room or speech privacy, ensuring conversations do not penetrate walls and travel to other rooms.
Jannatul believes Bangladeshi households are better suited for this compared to foreign structures. "In the US or Japan, where houses are often made of lighter materials, you can always hear what's happening in the next room. This is better managed in Bangladeshi apartments, as we use brick. But even that is not enough," she said.
For such situations, architects carry out insulation techniques in between the two walls to dampen and absorb the unwanted sound. After carrying out noise level calculations, the thickness of the insulation needs to be decided.
Generally, these materials consist of fabric which function as cushions, as well as cork sheet and glue and other soft materials that can dampen the noise.
Common sound insulation materials
For sound insulation, a large variety of materials are available, each with special qualities and uses. Choosing the best solution for a given project requires an understanding of these materials' qualities.
Fiberglass: It is affordable, lightweight, and simple to install. Typically, fiberglass insulation is placed in ceilings, floors, and walls to lessen the transmission of sound via the air.
Mass-loaded vinyl: MLV is a flexible, thick material that can be used to stop sound waves from traveling through it. It is frequently added as a layer to existing walls, floors, or ceilings to improve its ability to block out sound, especially loud music or heavy machinery.
Open-cell foam: Because of its porosity, sound waves can enter and be absorbed by this kind of foam. It is a practical way to enhance lecture halls, recording studios, and auditoriums' acoustics.
Cellulose: Cellulose insulation is blown into your home or building, so it can get into small spaces for maximum soundproofing impact. It's also high-quality temperature insulation, so you can reduce sound and improve energy efficiency.
Wooden acoustic panels: These acoustic panels are made from a combination of an acoustical felt backing, MDF, and real wood veneers. Their fluted wood panel design adds to their acoustic performance, as sound waves are caught between the slats and in the felt backing, reducing echo by up to 85%.
