Ovales Hörrohr

An elliptical acoustic vessel rests on a small pedestal between two people who use its openings to transmit or receive sound. The person on the left wears standard European dress, while the figure on the right wears a distinctive feathered headdress. The device is marked with the letters B, O, and C to designate the path of sound waves according to geometric principles.

Athanasius Kircher was a pioneer in the study of acoustics, which he termed 'phonurgia.' This diagram illustrates his belief in 'natural magic'—the use of science and geometry to produce seemingly miraculous effects, such as the amplification of sound or secret communication through walls and vessels.