A method is disclosed for testing hearing in infants based on pupil dilation response. It does not require sedation or depend on subjective judgments of human testers. Pupil dilation response to sound is measured by presenting on a display a visually engaging video containing periodic changes； presenting sounds synchronized with the periodic changes of the video； recording images from a camera directed in front of the display, where the camera is sensitive to infrared wavelengths； processing the images to measure pupil sizes； and processing the measured pupil sizes to determine, statistically, the presence of a pupil dilation response to the sounds.
