Informatics Publishing Limited

Naveen Garg ¹, Omkar Sharma ¹

Affiliations
1 Acoustics, Ultrasonic, Shock and Vibrations Standards, Apex Level Standards and Industrial Metrology Division, National Physical Laboratory, CSIR, New Delhi, IN

Abstract

The present work discusses the methodology and procedure followed at NPLI for calibration of charge amplifiers. The charge amplifiers are calibrated conventionally using a 1 nF standard capacitor and sine generator for gain measurements. An automated calibration system using B&K Calibration software in conjunction with a calibrated 1 nF precision adaptor controlled by Pulse Analyzer is also used for precision calibration of charge amplifiers for gain and phase measurements from 0.5 Hz to 20 kHz. The uncertainty achieved in gain calibration is reported in the present work.

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Mahavir Singh ¹, Omkar Sharma ¹, Dharam Pal Singh ¹

Affiliations
1 Acoustics Section, National Physical Laboratory, Dr. K.S. Krishnan Road, New Delhi, IN

Abstract

Penetration of exterior noise into a building occurs in many cases primarily through the window panes. An extensive study at the Acoustics Section of NPL provided a database of sound transmission loss measurements through many variations of glass thickness and air gap. Understanding the behaviour of the glass and cavity are an essential first step in designing or selecting window panes to attenuate outdoor noise. Sound transmission through window panes is governed by the same physical principles that affect walls, but practical noise control measures are influenced by the properties of glass and the characteristics of window assemblies. Increasing the glass thickness, for example, gives greater noise reduction at most frequencies, but the stiffness of glass limits the improvement. Using multiple layers (double or triple glazing) increases noise reduction at most frequencies, but this is dependent on the separation of the layers. The influence of typical window pane characteristics on sound transmission is discussed in this paper.

Keywords

Sound Transmission, Window Panes, Mass Law, Mass-Air-Mass (Cavity Construction).

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