An "Open-Back" design refers to a type of headphone or speaker that has an open rear, allowing sound to escape. This design creates a more natural and spacious sound, as it mimics the acoustics of listening to music in a room rather than in a confined space. Open-back headphones are often favored by audiophiles for their sound quality and comfort. However, the open design also means that sound can leak out, making them less suitable for noisy environments or for use in public spaces. Users may also experience less isolation from external noise, which can be a drawback for some listeners.