Sound consists of pressure waves in the air, whose intensity can be measured at different wavelengths or frequencies (number of cycles per second). The human ear is particularly sensitive to sound with frequencies ranging from 500 to 8000 Hz and responds in a non-linear manner.
Therefore, in order to measure the sound pressure level, a logarithmic scale based on hearing threshold is used.
The unit of measurement is decibel (DB).
For different frequencies of sound, the sensitivity of the human ear varies
Therefore, in order to judge the sound insulation performance of materials, we use the sound level weighting method according to “A curve”.
However, the sound in the building only needs to be considered in the range of 100 to 5000Hz, which can be divided into octave (the upper limit is twice the lower limit) or 1/3 octave.
Noise, which is unwanted, unpleasant and destructive, is increasingly appearing in our lives, affecting our comfort and even our health. Ordinary glass is not enough to block noise. However, now architects have been able to reduce the noise generated in urban life, even using Huakai sound-proof PVB intermediate membrane.
Sound-proof laminated glass is used in the exterior walls of buildings (standard windows, storefronts and curtain walls), providing significant sound transmission attenuation performance, reducing noise from traffic, aircraft, trains, buildings, etc. In indoor applications, such as partitions and windows, sound insulation laminated glass can help maintain the privacy of the conversation and create a relaxed and comfortable environment.
Huakai film sound-proof glass has good sound attenuation performance. With reasonable structure design, its single numerical level can reach 50-weighted reduction (Rw) or sound transmission level (STC), while the hollow glass device with 4mm glass [12mm air layer] 4mm glass is ~ 30RW or STC. The use of laminated glass with strong sound insulation can help protect people from noise transmission.
In addition to noise reduction, Huakai Intermediate Membrane can also provide other benefits, such as sunlight control function, safety function, security function and decoration function. Sound insulation sandwich glass made of three layers of PVB interlayer in acoustic engineering can reduce the sound to a greater extent.
When used in hollow glass devices, the thickness of different glass panels and gaskets must be specially designed to obtain the best performance.
It is found that glass panels can penetrate sound waves at two band levels, i.e. below 250 Hz and between 1000 and 3150 Hz (depending on thickness). These two effects are caused by the inherent mechanical resonance of glass and the coincidence phenomenon (the frequency at which the glass panel begins to vibrate).
(Source: conventional data of CEN (EN12758-1))
Sealed Glass (Hollow Glass Device)
In this case, the resonance frequency is inherent in the mass/air/mass system.
Resonance also occurs in the cavity separating the two glass panels. In fact, some waves are reflected by two panels, which results in cavity resonance.
The coincidence frequency is the same as that of glass components.
(Source: conventional data for CEN (EN12758-1))
Double-layer asymmetric glass panel
Hollow glass panels made of glass components with different thicknesses perform better, especially at high frequencies, because the coincidence threshold of the two components is not at the same frequency.
When the total thickness is equal, the performance of double-layer asymmetric glass panel is better than that of double-layer symmetric glass panel.