- Abstract Measured values of acoustic absorption often vary between the laboratory and the field due to deficiencies in standard measurement methods. This paper introduces a new method of measuring acoustic absorption in the field using a spherical microphone array. Plane-wave decomposition is used to separate direct energy from reflected energy when the array is placed adjacent to the absorptive sample. Additional signal processing techniques including the Dolph–Chebyshev beampattern and Delay-and-Sum processing are introduced and used to improve the method. The method is verified by simulation for normal and oblique incidence and by experiment for normal incidence.