The smallest sound pressure that may be detected in a conventional measuring system is determined by two noise sources. The first is a microphone itself, and the second is the preamplifier connected to the microphone. An experimental 1-in diameter microphone has been constructed, in which very low noise and broad bandwidth were the major design considerations. In the following, the results of measurements on the microphone are given, and the theoretical basis for noise in microphones is explained. It was found that only thermal noise in the microphone was important.
This paper costs $33 for non-members and is free for AES members and E-Library subscribers.