Cylindrical Nearfield Acoustical Holography: Practical Aspects and Possible Improvements

This chapter discusses Nearfield Acoustical Holography (NAH) for the characterization of cylindrical sources. Cylindrical NAH is an experimental air-borne characterization technique, and it is suited for any type of cylindrical source. NAH allows to evaluate sound intensity, pressure level and particle velocity. Practical aspects of Nearfield Acoustical Holography such as positioning error, measurement noise, hologram distance and measurement aperture are investigated and discussed with the aid of numerical examples. Moreover, a technique referred to as compressive sampling (CS) is discussed, aiming to reduce the number of sensors required by the classical NAH in the high frequency range.