What is Acoustic Performance and Why is it Important for Windows
When it comes to smart, sustainable living, acoustic performance is something to consider. But why is acoustic performance important? Well, if you live on a busy street, or in city locations, noise pollution can affect your life. Your mental health can suffer, too.
How can windows and doors help with noise issues?
Windows are now classified as wall assemblies. This is a new change for 2022. This means that there are new regulations for window and door manufacturers. So there is now a need for Thermotek to produce products that perform as a wall assembly. Windows fulfil many functions, including almost all functions of normal wall assemblies. Windows are the only element in a wall assembly that involves both heat loss and heat gain. They are a:
- water-shedding surface
- water-resistive barrier
- an air barrier
- a sound barrier
- a vapour barrier
- as well as providing insulation.
So it is now even more important to research a window’s acoustic performance. Everyone wants to experience peace and quiet. Imagine if you lived next door to an airport or if you are living on a busy road.
How would you measure the acoustic performance of a window?
This is a difficult question to answer. Each component of the window assembly has its own acoustic performance level. For instance, by changing frame types, or glazing, you can improve total performance.
The first step is determining what type of noise you are dealing with. What works well for speech volume between 2 apartments may not work well with band practice.
Step two is determining if you are trying to avoid outside noise (like traffic)? Or is it internal noise (such as within apartment buildings)?
Transmission means the sound is travelling. When sound moves from the inside of the room to the outside, there has been a Transmission. The walls absorb some of the sounds. But not all sound from inside will move to the outside. This is a “loss of transmission” or sound loss.
A decibel (dB) measures how loud the noise is. Think of dB as the volume knob on your radio. 50 dB is quiet while 140 dB is so loud it can immediately injure your ears. Sound is a vibration, right? Decibels are vibrations. You can feel these vibrations as pressure or density. If decibels are how loud the vibration or sound is, then the frequency is how sharp that sound is. Or how fast the vibration is. The unit of measurement for frequency is Hertz. When there is sensory overload, you feel pain.
How do you measure the acoustic performance of a window?
We work out the STC or OITC Score. STC means Sound Transmission Class. This measures the sound leaving from inside of the room to outside the room. For instance, this is relevant for apartments. OITC means Outdoor/Indoor Transmission Class. This measures how much of the outside sound is coming inside the room, home or building. The higher the STC or OITC rating, the higher the sound attenuation properties of the window. The glass, frame and construction of the window assembly influence its acoustic performance. The correct installation is also an important factor here.
Sound Transmission Class
STC gives you a rough idea of how much sound a window can reduce. It’s the most common sound reduction measurement to use. It also determines how much loss of sound is in the transmission. STC values focus on the calculation of transmission loss.
Outdoor/Indoor Transmission Class
The OITC’s original purpose was to check a product’s performance and exterior noise. Imagine living next to an airport, train station and so on. You’d want to keep that noise out. A higher number means better performance.
What are the best STC values?
The threshold at which privacy begins is STC 45. At this level, good soundproofing begins. Neighbours generally are not disturbed by very loud speech from inside. Whereas an average window has an STC rating of 25 to 30.
What is a good OTIC rating?
The OITC rating system measures the transmission of street sounds. For instance, car horns, sirens, construction, and low-flying aeroplanes. A higher OITC rating means better soundproofing properties of your external barriers. Outside noise is a bigger concern for Thermotek’s customers. In this case, the OITC rating includes the 80 to 100Hz frequencies. OICT measures low to mid-frequency sounds, so it’s a great rating system for windows.
Thermotek can help you with your individual sound issues.
The main question you need to ask is, what level of noise frequency are you dealing with? That will help you determine your rating of choice. Whether it’s STC or OITC.
OITC measures lower frequencies. There are also factors that can affect the ratings of a window. These factors include glass thickness, insulating gas, spacer type, and some glass lite.
Thermotek is a Melbourne-based manufacturer of double glazed uPVC windows and doors. Check out our great Google reviews here. We create quality, sustainable products for an energy-efficient future. We offer a range of colours and styles. Get in touch today with any questions. We look forward to helping you on your double-glazing journey.