Not necessarily. Moreover, simply increasing the width of the spacer bars is not an effective way to enhance the sound insulation effect.
The sound insulation performance of insulating glass mainly depends on the combined effect of the following factors, and the width of the spacer (insulating layer) is just one of them.
The principle of sound insulation: the mass-law and resonance effect
Mass-law: For most common mid - and low-frequency noises (such as traffic noise and voices), the surface density of the glass itself (i.e., thickness and weight) is the primary factor for sound insulation. The thicker and heavier the glass is, the less likely it is to be vibrated by sound waves, and the better its sound insulation effect will be. This is why soundproof glass is usually made by combining glass sheets of different thicknesses (such as 5mm+6mm) to avoid resonance.
Resonance and coincidence effect: Sound waves can cause glass to vibrate. If the thickness of two pieces of glass is the same, their inherent vibration frequencies are also the same, which is prone to resonance and thus greatly reduces the sound insulation effect. The use of glass of unequal thickness is the key technology to break this resonance and improve sound insulation performance.
The true function of the hollow layer (spacer width)
The hollow layer is filled with dry air or inert gas (such as argon) inside. Its main functions are:
Changing the sound transmission path: When sound travels through the "glass-air-glass" path, it will be reflected and attenuated multiple times in the air layer.
Buffering effect: The air in the hollow layer acts like a spring, partially absorbing and buffering the energy transmitted by sound waves.
Avoiding resonance: A hollow layer of appropriate width can change the vibration frequency of the system, which helps to offset the resonance frequencies of the two pieces of glass.
So, is it true that the wider the spacer, the better?
Not really. There is an issue of "optimal width" here.
When the width is too small (such as less than 6mm) : The air inside the hollow layer will act like a spring, tightly coupling the two pieces of glass, making it easier for sound to pass through directly and resulting in poor sound insulation.
When the width gradually increases (such as 9mm - 15mm) : the spring effect of the air layer weakens, and the sound insulation effect on medium and low-frequency noise will be significantly improved.
When the width is too large (such as over 20mm) : The air inside the hollow layer will start to convect. This convection will form a new "sound bridge", which is actually conducive to the transmission of mid and low-frequency sounds, resulting in a decline in sound insulation effect. At the same time, overly wide insulating layers also impose higher requirements on the strength and stability of the glass.
The conclusion is that there is a critical point of diminishing returns for the width of the hollow layer, which is usually between 12mm and 18mm. Beyond this range, further increasing the width will have a negligible effect on the sound insulation effect, and it may even deteriorate.
A more important factor than the width of the spacer
To achieve better sound insulation, you should give priority to the following points
Glass thickness and combination: Using a combination of glass of different thicknesses (such as 5mm + 6mm) is one of the most cost-effective ways to enhance sound insulation. This can effectively stagger the resonant frequency.
Use laminated glass: This is the key to sound insulation. Between two pieces of glass, a layer of PVB film is sandwiched. This film is a viscoelastic material that can effectively absorb and consume the energy of sound waves, especially providing excellent isolation for medium and low-frequency noises (such as the roar of traffic). The combination of "insulating + laminated" (i.e., laminated insulating glass) is one of the highest standard configurations for soundproof doors and Windows at present.
Hollow layer gas: Filling inert gases with higher density (such as argon) can improve sound insulation and heat insulation performance to a certain extent, but its effect on improving sound insulation is not as obvious as changing the structure and thickness of the glass.
Sealing performance: The sealing performance of the entire window (including profiles and sealing strips) is of vital importance. Even if glass has excellent sound insulation, as long as there is a gap, sound will come in.
Summary
The width of the spacer bars is not necessarily the wider the better. There exists an optimized range of approximately 12mm to 18mm.
Simply increasing the width of the spacer bars has a limited effect on improving the sound insulation effect.
The effective sequence for enhancing sound insulation is:
First choice: Use laminated insulating glass.
Second choice: Use insulating glass of unequal thickness.
Finally: Select the width of the hollow layer within a reasonable range (such as 12A-18A).
Therefore, if you are choosing doors and Windows for sound insulation, please do not be deceived by the promotion of "ultra-wide insulating layer". You should focus on whether laminated glass and unequal-thickness glass combinations are used.
