Anechoic chambers are typically qualified by comparing sound pressures at several radial distances from a sound source and verifying that they follow the spherical spreading law within specified tolerances. While this technique is useful, it may not sufficiently characterize free-field variations at fixed radial distances and numerous angular positions, as are commonly used for directivity, sound power, and other important acoustical measurements. This paper discusses a technique to detect angular field deviations in anechoic chambers. It incorporates a loudspeaker in an altazimuth mount, an adjustable-radius boom arm, and a precision microphone. The boom arm and microphone remain in line with the loudspeaker driver axis at a fixed radius while the system rotates to specified polar or azimuthal angle increments. In an ideal free-field environment, the frequency response function from the loudspeaker input to the microphone output should remain consistent—regardless of the system orientation. However, in typical anechoic chambers, they vary. Standard deviation calculations over many angles reveal frequency-dependent departures from the ideal, especially for narrow-band data. The results show the impact of these discrepancies for multiple-angle measurements and how they change with radial distance from the source.