US Patent 8259959 Toroid microphone apparatus

A video teleconferencing directional microphone includes two microphone elements arranged coincidentally on a vertical axis. The two microphone elements are placed on a supporting surface so that a first microphone element is on the surface, and the second microphone elements are elevated above the supporting surface. The directional microphone also includes filters, an adder assembly, and an equalizer, which are used to shape the directivity pattern of the directional microphone into a toroid sensitivity pattern. The toroid sensitivity pattern increases sensitivity in the direction of a sound source of interest, while simultaneously reduces sensitivity to any sound waves generated by noise sources from certain elevation angles.