The condenser microphone and some of its uses in laboratory investigations

The development of techniques for measuring sound pressures are discussed, with special reference to the accuracy of various methods. After comparing the advantages and disadvantages of different kinds of laboratory microphone in use today, the characteristics of the condenser microphone are discussed more fully. The theory brings to light the factors which govern the frequency response, sensitivity, acoustic impedance, and other important qualities. Then, following some comments on the principles of designing miniature microphones, methods of calibration are discussed. Taking the loudspeaker as an example of electro-acoustic equipment which is to be investigated, most of the possible acoustic test arrangements are considered, partly with a view to deciding which, if any, give the best objective criterion of fidelity. Other uses of the condenser microphone are also discussed briefly.