THE SCIENCE OF SOUND
WHAT IS A SOUND?
Sound is a pressure wave that travels through a medium to your ear, at which point it causes small membranes and bones to reverberate. These vibrations are transmogrified into electrical signals, which in turn travel to your brain, where they’re interpreted into words, songs and signals.
So the answer to the question is, ‘No, not unless there is someone in the forest to hear it fall!’
As opposed to sound, noise is simply defined as an irregular, fluctuating wave pattern that is loud or unpleasant or that causes disturbance.
Formed of compressions and rarefactions, sound moves at different speeds and with varying degrees of ease through various mediums. Contrary to popular belief, sound actually travels rather ineffectively through air as the inelasticity of the gases that form our atmosphere does not make it a good conductor. On the other hand steel, which is more elastic, allows sound to travel rapidly and with ease.
On the other, other hand, sound won’t travel anywhere at all in a vacuum. You see, sound requires matter to transmit its energy, and denser, more elastic materials work best as the molecules within the material make it easier for the wave to propagate.
Soundproof windows are designed on these principles; using materials that will not easily allow transmittance of the wave.
UNDERSTANDING SOUNDPROOF GLAZING
Typically glass is a good conductor of sound, which makes it bad for soundproofing. Due to this fact, soundproof glazing needs to disrupt and dissipate sound waves differently. It does this in a few ways:
All materials have a ‘natural resonance’ depending upon their size, shape and thickness. This frequency is the pitch at which the material will vibrate easily, meaning that it will allow noises at this frequency to be passed on without resistance. In order to combat this in soundproof glazing, glass of two different thicknesses are used.
By having two different natural resonance frequencies, noises of a certain pitch aren’t allowed to pass through as easily as they would with traditional double glazing, or single pane windows. This works optimally when the two sheets of glazing have a differential in thickness of 30%.
POLYVINYL BUTYRAL (PVB)
In noise reduction glazing, the panes of glass are separated by a layer of PVB. This is designed to prevent sounds in the 1000 – 3000 Hz range (the most sensitive range for humans) penetrating through the glazing by dissipating the wave. PVB typically offers a reduction of around 10 decibels, which is what we consider a 50% reduction in perceived loudness.
MICRO RUBBER SPACERS
Fitted around the windows are micro-rubber spacers. These create a barrier between the window frame and the sill, preventing noise emanating from the timber.
As sound cannot travel in a vacuum, some highly advanced glazing units employ a vacuum between the glazing, which will stop sound dead in its tracks.
Throughout this website, we talk about decibel reductions, but what is a decibel?
A decibel is a measure of intensity of a sound against a set logarithmic scale. As opposed to a linear scale (which increases by a set number with each unit), a logarithmic scale (which increases by a multiplication) is used in order to deal with the fact that sound has a massive range of quantities. Whilst this may sound complicated, we use a logarithmic scale to make it easier for us to understand sounds, as the numbers would be too large for us to grasp otherwise.
The difference is practically unnoticeable.
The difference is just perceptible.
The difference is clearly audible.
The difference perceptibly halves / doubles the noise.
If this doesn’t make sense, then consider that the optimal noise level for a bedroom is around 30dB. However typical noise pollution from a busy road can raise this to 75dB, at which level you will find it very difficult to sleep.
By installing windows with a noise reduction quality of 45dB, we can bring this right down to the optimal level and give you a peaceful night’s sleep.
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