Low-frequency hum in audio track — typically 50/60 Hz mains hum from equipment, power lines, or poor grounding. Remove with notch filter or ground lift.
It lurks in every set sound recording — that deep, constant hum that stubbornly persists on the track and becomes a nightmare in post-production. The buzz is the classic low-frequency artifact that arises when power lines, faulty ground connections, or poorly shielded cable runs contaminate your audio recording. In Europe, the power grid operates at 50 Hz, in the USA at 60 Hz — and it's precisely these frequencies we hear as a disturbing hum. Sometimes double that also creeps in (100/120 Hz) if multiple harmonics penetrate simultaneously.
The source is almost always in the cabling or power supply of your audio equipment. A mixer placed directly next to a power outlet will pick up hum. An XLR cable running across power lines instead of under or over them? Buzz magnet. A poor ground connection between devices — especially critical with long cable runs or multiple sources with different ground potentials — and suddenly the fundamental frequency oscillates through your master track. Professional frequency: Buzz appears when you combine multiple wireless lavaliers, a camera microphone input, and a mixer with weak shielding at the same time.
On set, it can be prevented: Never run XLR cables parallel to power lines — perpendicular or diagonal, always. Test the ground lift switch on the mixer if the connection is balanced. Connect all devices to the same circuit or use an isolation transformer. Cable quality is not optional — cheap cables don't shield. For wireless systems: position the antenna correctly and place the receiver on a stable surface, not on metal.
In post-production, the editor gets a notch filter — a very narrow EQ band precisely at 50 or 60 Hz with a high Q value, which pulls out the hum without destroying everything else. Some DAWs have specialized buzz removal plugins that address the fundamental and harmonics simultaneously. But honestly: prevention beats correction by a mile. Having a clean recording without buzz is faster than an hour of post-processing later.