Noise abatement circuit

A noise abatement circuit comprises a sound card, a speaker and a power supply, wherein the sound card is used for processing audio files, the speaker is used for amplifying audio signals outputted by the sound card, and the power supply is used for supplying power for the sound card. A grounding circuit is connected onto a transmission line for transmitting the signals outputted by the sound card to the multimedia speaker, and the signals on the transmission line are grounded by the grounding circuit when the power supply stops supplying power for the sound card.