A ground loop isolator is a device used to eliminate unwanted noise in audio systems caused by ground loops. Ground loops occur when there are multiple grounding points in an audio setup, leading to interference and hum in the sound. By breaking the electrical connection between devices, ground loop isolators help ensure a cleaner audio signal. These isolators typically use transformers to separate the ground paths, allowing audio signals to pass while blocking the noise. They are commonly used in various setups, including home theaters, professional audio equipment, and musical instruments, to enhance sound quality and reduce interference.