| Abstract: |
Historically, various techniques have been used in acoustics to attempt to establish and to measure sound pressures in the pressure field (spatially uniform amplitude of sound pressure, as in a suitable coupling cavity that is small compared to a wavelength of sound) and in the free field (plane progressive sound wave at a specified angle of incidence in the absence of reflecting surfaces). At present, over a broad range of frequencies the most accurate, precise, and convenient methods involve the primary calibrations of laboratory standard microphones by reciprocity techniques. Some issues and parameters in these techniques that need to be considered in comparisons, and selected previous interlaboratory comparisons themselves, are discussed. Recommendations relevant to a key comparison already identified, as well as future work areas, are presented. |
