Noise-cancelling earplugs

A noise suppression system addresses the electrical disturbances that contaminate a hi-fi system’s power supply: these high-frequency interferences (EMI and RFI) injected into the mains by switching power supplies, LED lighting, motors or digital devices in the home. The principle is to filter this noise before it reaches the audio electronics, where it can find its way into the power supply of the components and interfere with playback. Two approaches coexist. Series filtering inserts components into the current path to block unwanted frequencies, effective but liable to restrict dynamics if poorly calibrated. Parallel filtering connects alongside the signal and absorbs interference without being placed in the current path, a passive approach that does not alter the waveform. The benefit depends on the condition of the mains: an installation near noise sources or on a shared line benefits more than an already clean circuit. One point to keep in mind: these devices treat noise coming from the mains, not noise that equipment sends back and forth between each other or that is picked up by the antenna. The function must still be distinguished: filtering noise, protecting against lightning and regulating voltage are three separate roles that a single unit does not always fulfil. For complete mains treatment, a power conditioner combines filtering and regulation, a surge-protected power strip adds protection against power surges, and the power supply to each component runs through a shielded power cable.