The shape of three-dimensional cavities affects the timbral quality of sound sources located within them. Moreover, the resonances of the cavities may impress a sort of pitch to noise-like excitation sounds, and the pitch height is somehow related to the size of the cavity. It is interesting to investigate how differently-shaped enclosures give rise to different perceived pitches. From a first experiment, it seems that when comparing the pitch of a cube with the pitch of a sphere, subjects actually match the volume of the two cavities. On the other hand, a second experiment shows that the comparison between the pitch of a spherical resonator and the pitch of a decaying sinusoid triggers a different listening mode, where subjects tend to match the single, most prominent resonances with the test sine tone. Understanding how we perceive the pitch of basic shapes may help the task of designing resonator models for auditory display, as the pitch control can be effectively decoupled from the shape control.
