Perrin Meyer

The analysis, interaction, and measurement of loudspeaker far‐field polar patterns

This paper discusses some issues related to the measurement and representation of loudspeaker far‐field polar pattern data (also known as directivity patterns). The mathematical framework of this method is based on approximating the time‐harmonic far‐field complex acoustic pressure field using the sum of spherically weighted acoustic point sources. One issue that is discussed in detail is a method where the far‐field polar pattern is estimated by rotating a loudspeaker on a turntable and measuring the response at equally spaced intervals. It is often asserted that in order for the far‐field data to be most useful, this ‘‘point of rotation’’ must correspond to an ‘‘effective acoustical center.’’ However, this location is often not known a priori, and often a single ‘‘effective acoustical center’’ does not exist or varies with frequency. A simple mathematical transform is developed to move the ‘‘point of rotation’’ of a measured far‐field polar pattern to a different location, simplifying the choice of a ro...