Reducing measurement errors: Taking the design of microphones to the limit

It is impossible to make one microphone that covers all possible applications. In the real world, the properties of a microphone are the result of a number of carefully chosen compromises based on the anticipated measurement situation and the measurement equipment. The electroacoustic properties of condenser measurement microphones are rigidly bound to the physical properties of the microphone cartridge and the electrical properties of the preamplifier. This means that in the design of a measurement microphone the challenge is to find the right balance between the various physical properties of the microphone. However, recent development in simulation models, construction technology, and knowledge of material properties has opened for the design of microphones that has pushed the limits. A new class of general purpose measurement microphones has been born. In this paper, the physical properties that determine the electroacoustic properties of a condenser microphone are reviewed, and the various compromises that must be chosen are discussed. The possibilities and limitations in microphone design are illustrated with examples of the newest microphone designs from Brüel & Kjær.