Technical Data>Noise Control

Until the ’70s, windows had been the weak link in building enclosure devices in terms of noise transfer.
Today, however, a wide variety of glass types and carpentries brings us a simple and efficient solution to the problem of noise insulation for residential, commercial and institutional buildings.

For a better understanding of the sound insulation properties that glass may offer, it is elemental to first understand the practical meaning of a decibel (dB), the unit used for measuring sound pressure and that gives us an idea of its intensity.
Unlike many other units of measurement commonly used, such as the meter, whose magnitude varies in a lineal fashion, the decibel (dB) varies logarithmically.
This means that every time the sound pressure increases10 (dB) the intensity of the sound rises to the tenth power.

Grafico de intensidad del sonido

It is common knowledge that 80 m is twice as long as 40 m; but, when it comes to measuring sound pressure, simply calculating its double amount will equal to a much greater increase in its intensity.
For example, the chart illustrates that 80 (dB) of sound pressure is not the double of40 (dB); rather, it equals to a value that is 10,000 times higher. The higher the sound pressure becomes the more endeavouring the task to insulate against noise transfer.
Low sounds (low frequencies) are more difficult and costly to insulate with glass than high sounds (high frequencies).

Put simple, a window with an average sound insulating capacity of 30/33 (dB) is said to have good sound controlling levels.
The following data serve as a guide to demonstrate how people perceive an increase or decrease in the sound pressure.

  • Normally, the ear cannot perceive a variation of 1 or 2 (dB) in the sound pressure.
  • A variation of 3 (dB) will go unnoticed if there is a lapse of time in between the sounds
  • A variation of 5 (dB) can be easily noticed under high sound pressure conditions
  • A variation of 7 (dB) will never go unnoticed by the ear, given that it practically means a duplication of the sound pressure.

Interior Noise – Recommended Levels
The following are the values usually recommendable for a series of business or typical activities in regards to the interior sound comfort:

Grafico de niveles recomendados de ruido

Sound Insulation
The following are the values usually recommendable for a series of business or typical activities in regards to the interior sound comfort:

Grafico de aislación acústica

RM
Average sound reduction index. It is the arithmetic value of the sound insulation values presented by a building element ranging between 100 and 3150 Hz.

RW
This represents the sound insulation value of a building element, with the human ear as reference. In figures, it may not exceed the RM average value by more than 5 (dB).

RTRA
Neither RM nor RW can be used to estimate the interior noise levels. Rather, an idealised, but typical, spectrum of road traffic noise is adopted. This represents the attenuation, in dBA, which the window can achieve in mitigating road traffic noise.