Window Options
Reducing Outside Noise

Where you live

Homes near traffic, trains, or airports get more outside noise.

Insulation

Thin walls or poor insulation let more sound through.

Window size and number

Bigger or more windows can let in more noise.

Window quality

Double or triple-pane windows block sound better than old single-pane ones.

Installation and frame

Good installation and solid frames help keep noise out.

Frequency (Hz)

Measures the pitch of sound. Higher frequencies are easier to block than lower ones. Frequency, measured in Hertz (Hz), refers to how many wave cycles occur per second. Humans hear from 20 Hz to 20,000 Hz, while dogs can hear up to 65,000 Hz. Higher frequencies mean higher-pitched sounds.

Decibels (dB)

This unit measures the amplitude pressure (loudness) of sound. This sound pressure scale begins at 0 decibels (the threshold for audibility for humans). The higher the decibels, the louder the sound.

Sound transmission

Sound transmission is how sound waves travel through air, water, or solid materials. It's measured in decibels (loudness) and hertz (pitch).

Material stiffness

Stiffness refers to how elastic a material is. Sound travels faster through stiffer materials (like steel) and slower through less stiff materials (like foam), which can absorb and dampen sound energy.

Material density (mass)

Denser materials (with more mass per volume) can slow down sound. However, stiffness usually has a greater effect on sound speed than density alone.

Sound damping

Damping refers to any technique used to reduce sound transfer between spaces. Window makers use methods like laminated glass or insulating spacers to minimize sound.

Sound absorption

This is how much sound energy is lost as it passes through a material. For windows, it’s the percentage of sound that doesn’t enter your home.

Soundproofing

Soundproofing blocks sound from entering or leaving a space. It involves methods like adding barriers, increasing distance, or using sound-dampening materials. True soundproof windows require every part—from glass to frame—to be optimised for sound reduction.

Sound leakage

Sound leaks occur wherever outside noise enters a home — through old windows, poor seals, vents, cracks, or under-insulated areas.

To compare windows for sound performance, look at these two ratings:

STC (Sound Transmission Class)

Rates how well a window blocks higher-frequency indoor sounds like voices or TV. Typically ranges from 20 to 60+ (no specific units, just a rating). Test Standard: ASTM E90 / ASTM E413.

OITC (Outdoor/Indoor Transmission Class)

Measures performance against lower-frequency outdoor noise, such as trucks or aircraft. Typically ranges from 20 to 40+ (no specific units, just a rating). Test Standard: ASTM E1332.

To reduce sound transmission, window manufacturers use a few strategies:

Laminated glass

Laminated glass is made by bonding two glass layers with a strong plastic layer in between. Even if it breaks, it stays together. North Star Windows offers a version with 6mm laminated glass on the outside and 3mm regular glass on the inside. This setup changes how sound travels through the glass, reducing noise. It also adds security because the glass holds together when shattered.

Triple-pane glass

Triple-pane windows can block more sound than double-pane windows — sometimes improving noise reduction by up to 7 STC points, especially if the panes are spaced well. They work by adding weight and increasing the air space between the layers, which helps block sound.

Dissimilar glass panes

Some windows use two glass panes of different thicknesses — for example, one 1/8 inch and the other 1/4 inch. Because each thickness blocks different sound frequencies, the window can reduce a wider range of noises.

Frame and sash material

The materials used for the window frame and sash affect how well a window blocks sound. Vinyl or wood is better at reducing noise than aluminium, which carries sound more easily. Some companies add foam or use special chambers in the frames to help reduce noise. Not sure which works better? Compare their STC ratings.

Type of window

The window style also affects how much sound gets through. Picture windows block the most noise, followed by casement, hung, sliding, and awning windows. To know for sure, check the STC rating for each type.

Specialised soundproofing windows

Soundproof windows are made specifically to block as much noise as possible. They’re more expensive because every part is designed for sound reduction. Soundproof windows are not typically offered by most window replacement companies. For extreme noise issues you may need to hire an acoustic consultant

Casement windows

Close tightly, forming a strong acoustic seal.

Awning windows

Similar to casements and effective in smaller spaces.

Fixed/picture windows

No moving parts means fewer gaps — great for blocking sound.

If you are not yet in the market for replacement windows, there are some quick-fix solutions that may offer some relief from external sound.

Sound-dampening window films

Aftermarket film laminates can filter out as much as 5 decibels of sound, according to some manufacturers. Typically made with 3 layers, the centre one does all of the sound blocking. The two layers on either side of it are made from polymer and support the product’s application and aesthetics. These films can be installed on virtually any type of window or glass.

Curtains & blinds

While window coverings alone can’t make your home soundproof, they can absorb noise coming through the window and help reduce exterior noise. Look for a honeycomb design, which can insulate your windows from the heat and cold as well. There are plenty of companies and solutions out there to meet your acoustic and aesthetic needs.

Window inserts

Inserts can be installed behind an existing window, adding dead, sound-reducing air between the principal window and the new interior insert, which can have an STC rating of 38 up to a 95% noise reduction, depending on the size of the window opening and type of noise.

These windows create large airspaces between the set of 2 windows, which kills noise by disrupting the sound waves. Note: These windows are typically made as non-operational and will prevent access to operational windows.