Acoustics - Inside out
How sound effects your health and what to do.
Noise – an unwanted sound.
Let’s think for a moment about when acoustics play a role in the enjoyment of your home and how it effects your health. Think of the sound of the wind rustling the leaves outside your windows, of the birds singing. Now think of the sound of the fridge, the dishwasher, your heels clicking across the tile floors. Now shift to the sound of your kid’s music blaring from his room. Or traffic honking in the busy street outside.
Our human bodies react to loud noises as if they are a precedent to danger – which creates stress hormones in the body and triggers the fight or flight reaction. Stress feels bad, and long-term exposure to stress can have detrimental effects to our health. According to the World Health Organization, environmental noise was directly linked to cardiovascular disease, a decrease in sleep quality, and cognitive impairment.
Think of when you want or need quiet – like during a zoom call in your home office or at bedtime after a long day. The acoustical properties of a room should be designed to support the activity of the room and the surrounding rooms.
Acoustics is a specialty in interior design – whether the desire is to enhance your garage band’s radical tunes, build a theatre room, suppress outside traffic noise, or simply create a calming environment, acoustical design is an awesome aspect to creating a healthy environment to live, work and play.
Do you want sound that is being made within the room to stay in the room or do you want to keep sound out of your space? When figuring out how to incorporate sound design in a room, start with a conversation about the room itself, the use of the room and the type of noise that you want to “control”.
What makes noise noisy?
When a sound is made in a room, it interacts with the surfaces of that room. Depending on the material it hits, sound can transfer or bounce across walls and through floors, or it can be absorbed into the surface.
Hard surfaces and large open spaces cause reverberation – sound bouncing (kind of like an indoor echo, or lingering noises). The harder the surface and larger the room, the more sound will reverberate. High ceilings can also make sound hard to control. Tile, drywall, concrete, wood, and glass all exacerbate unwanted sound.
In short, to buffer sounds (decrease reverberation) within a room, add soft materials, like upholstery, curtains, rugs and wall hangings. The more you add, the more sound will be absorbed.
Do note however, these materials don’t stop sound or soundproof a room, they simply absorb sound and reduce echo.
The flip side
There are two sides of acoustical control, absorbing reverberation as discussed above and blocking sound (soundproofing). Absorbing reverberation in a room and blocking or reducing sound are done in two very different ways and with different products and approaches. There are products that absorb sound within a room, and there are other products that will block or stop/reduce sound transmission. And yes, there are also composite products that do both. This is why it's important when considering the design of a room, we want to know what each room will be used for and if any acoustical additions will make sense.
Products that are used to block sound are inside of the wall or ceiling – as part of the construction of the structure. They can be dense, heavy materials or materials that will decouple the wall assembly – and due to their density, often reflect the sound back into the room rather than the sound penetrating through to the other side.
A good analogy I recently read by Acoustical Surfaces, Inc., experts on soundproofing, acoustic noise and vibration control:
Imagine you are building an aquarium to hold water. Sound acts like water when you are trying to control it. If you used sponges as the walls, they would absorb the water but quickly let all of it seep through to the other side. Glass and good seals block the water and keep it in place. Acoustical materials made from soft, squishy things like sponges are going to absorb. Dense, heavy, air-tight materials will block.
There are three basic ways to block sound: Increase the mass and density (weight) of the wall to make it heavier, decouple the wall assembly (where one side of the wall doesn’t touch the other) or dampen the vibration energy of the wall.
A room’s walls, ceiling, and floor must be dense and isolated from the rest of the structure for soundproofing, and the air gaps must be sealed – such as doors and windows, heating and cooling vents, and electrical sockets. Think of soundproofing like weatherproofing, if air can get in, so can sound.
As sound effects our health, it’s important to consider how when designing your space and then find ways to either live with it or control it when needed.
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