Voltage to pressure conversion: are you getting `phased' by the problem?

Abstract

The process of calibration provides the user with the sensitivity data necessary to convert the voltage measured at the end of the hydrophone cable to an acoustic pressure. This paper addresses the precise nature of how this data is used. Most regulatory standards simply require the user to use the sensitivity figure at the acoustic working frequency of the source in conjunction with a known (or pre-specified) `flatness' criterion for the overall frequency response. This paper questions the validity of this approach, and looks at the differences that can be obtained when the voltage to pressure conversion is accomplished by means of a deconvolution process that utilises all of the frequency response curve (as opposed a single data point). Theoretical and experimental comparisons between single frequency and full waveform deconvolution are presented.