Corded foam earplugs are used for hearing protection in noisy environments by reducing sound levels, with the cord preventing loss and allowing them to rest around the neck when not in use. Common uses include workplaces with high noise levels such as construction, manufacturing, and mining, as well as for personal activities like sleeping, traveling, or hobbies. They are a practical choice when workers frequently insert and remove earplugs, as the cord ensures they remain readily available and prevents them from getting misplaced.