A sample of glass is glazed in an acoustic test chamber where it is subjected to various frequencies. Sensitive microphones compare the source side with the receiving side to produce a plot and measurement of the effect of the glass at each frequency. The chamber is calibrated to ensure that it is the glass performance only that is being measured. In the field, anyone with a noise meter can potentially measure noise. However, it is a specialist’s field of work, and should be undertaken by noise consultants who have the knowledge to do a noise survey and present the information in a proper and useful way. Inexperienced use of a meter will not produce information that can be relied upon.