Noise Reduction

Alongside significantly improved thermal performance, double glazed windows also provide substantial acoustic benefits, minimising sound intrusion into the home. Acoustic performance is affected by a variety of design elements, but your choice of windows is likely to be the single biggest area of improvement. Our high-end Miglas acoustic glass windows significantly outperform other windows on the market.

 

Acoustic performance is measured through the Sound Transmission Class (STC) rating, which measures the amount of sound a product will prevent or stop, known as Transmission Loss. The higher the STC rating, the better the product. An STC rating measures Transmission Loss in decibels (dB) across 16 different frequencies per ASTM E413. This provides an overall understanding of a product's performance in a broad spectrum of acoustic applications. Lower frequencies (like bass tones and truck engines) are harder to minimise than higher frequencies (like whistling and conversation). An STC rating gives an indicative figure of how many dB of sound a product prevents.

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It is also important to note, that dB is a non-linear scale so whilst a change of 1dB is almost imperceptible, a change of 10dB is twice, or half, as loud. From a volume perspective, 50dB is quiet, while 140 dB is so loud that it can immediately cause hearing damage.

 

In general, the thicker the glass of a window, the better its acoustic performance. However, this effect can be restricted at certain frequencies where the ‘coincidence dip’ occurs. This is the frequency at which the glass panel vibrates in unison with the frequency of the source sound. When this happens, the acoustic insulation properties of the glass are reduced. The coincidence dip for 4mm float glass is approximately 3125Hz, and around 1040Hz for 12mm float glass. An effective design principle in double glazing is to vary the thickness of the glass panes to create an ‘overlap’ where the coincidence dip occurs, maximising acoustic performance — a design not possible with single glazed applications.

Below are some ‘centre of glass’ STC ratings of common acoustic glazing combinations, highlighting the varying levels of performance that can be achieved. The combination possibilities are limitless, and we are here to ensure you obtain the most cost-efficient and effective solution for your project, whatever your objectives.

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