We propose a baffleless circular array of radially outward facing cardioid microphones that produces standard ambisonic signals. The array produces an $N$th-order ambisonic signal from $2N+1$ microphones. It can be seen as a baffleless variant of the previously proposed equatorial microphone array, which uses a rigid spherical baffle. The simplicity of the microphone arrangement comes at the price of not being able to extract certain spatial information from the captured sound field. The ambisonic output signal represents a horizontal projection of the captured sound field. We demonstrate that interaural elevation cues are maintained when binaural rendering is performed despite the horizontal projection.
