Optical Wonderful
Illusion Category

Sound Illusions

A bonus category: illusions that trick the ear and brain the way visual illusions trick the eye, from speech perception quirks to tones that seem to rise forever.

Auditory

McGurk Effect (Audio-Visual Illusion)

Dub the sound 'ba' onto a face saying 'ga' and most people hear 'da', a syllable nobody spoke. Why seeing a mouth changes what you hear, and why not everyone does.

 Auditory

Shepard Tone (Auditory Barber Pole)

A scale that seems to climb forever but keeps returning to where it started. Play it in your browser and watch the tones that create the endless rise.