As a general rule, increasing mass will improve sound insulation. Brick and concrete walls have stronger sound insulating values because they are of greater mass when compared to glass. But because we need glass to see through, to provide natural daylight and to enhance a building look and appeal, the need for greater sound control when using glass becomes more important.


Sound originates from something that vibrates which generates changes in air pressure. Frequency is used to refer to the number of vibrations or changes in air pressure per second. The value given is usually expressed as hertz (Hz) (i.e. 750Hz).


Different sounds produce different frequencies. Traffic noise as an example, produces sounds most intensely in the lower frequency range. The Intensity or Loudness of a sound is of most concern to people. The loudness of a sound is rated as Decibels or ‘dB’.


Where there is a noise problem to solve, three areas have to examined:

• determine and/or measure the external noise;
• sound insulation rating of the window system/glazing; and
• the resultant noise level in the room.

Having determined the external noise level rating and desired internal noise level for a given room, the next step is to substract the glass reduction rating.


For example:

o External noise source – Loud traffic 80dB
o Bed room recommended noise level -40dB
= 80dB – 40dB = 40dB rating required for window/glazing system
= 12.5 VLam Hush in single glass form