Directional pinna for microphone

The outer part of the human ear, called the pinna, has a complex shape containing many folds. It selectively amplifies and attenuates different sound frequencies depending on which direction the sound is coming from. This, combined with information about the volume and timing of sounds reaching each ear, allows the brain to pinpoint the direction the sound is coming from.

This thing is a design intended to provide similar directional sensitivity to a microphone, e.g. for a robot. The spiral ridge along the inside interacts with the outer lip and the microphone hole at the apex, causing two resonant peaks in the sound spectrum. The frequencies of these peaks vary with the direction of the incident sound. By measuring these peaks with FFT analysis, it is possible to determine the sound's direction within the projected shape of the cone.

Depending on the size of your microphone, it may be necessary to cut off some of the material near the apex. I designed my thing for this microphone: https://www.adafruit.com/product/1713 however I still required to trim the thing in order to fit the mic in (it fits snugly).

In theory it should be possible to pair a pinna-attached mic with a bare mic and train an AI to recognize the direction of each incoming sound.