Audio CAPTCHA

An auditory alternative to visual CAPTCHAs, typically presenting distorted spoken letters, numbers, or words that users must transcribe. While intended as an accessible alternative for blind users, research shows audio CAPTCHAs have success rates of only 43-50% for screen reader users—far below the 90% threshold considered acceptable. Problems include interference between CAPTCHA audio and screen reader output, heavy distortion making content difficult to understand, and the linear nature of audio requiring users to remember sequences while navigating to input fields.