Passive noise isolation refers to the ability of a material or device to block or reduce unwanted sound without the use of electronic components. This is typically achieved through physical barriers, such as thick walls, soundproof windows, or specially designed earplugs. These materials absorb or reflect sound waves, preventing them from entering a space or reaching the listener. In the context of audio equipment, passive noise isolation is commonly found in headphones and earbuds. These devices use cushioned ear cups or snug-fitting designs to create a seal around the ears, minimizing external noise and allowing users to enjoy their audio content without distractions.