Audio interference—neighboring frequencies or signals bleed into one channel. On set heard as hum, buzz, or unwanted signal contamination.
On set, you notice it immediately: suddenly a hum under the dialogue, a metallic chirp, or—worse—the voice from the neighboring wireless microphone bleeds into your channel. That's crosstalk, and it happens more often than you'd like. The cause usually isn't in the air, but in the cabling, connectors, or the electromagnetic proximity of signal lines to each other.
Technically, crosstalk arises from capacitive or inductive coupling—your audio line acts as an antenna for interference signals radiating from power cables, Wi-Fi routers, radio transmitters, or even the lighting dimmer system. In the audio mixer or at the wireless receiver, two closely spaced channels can also bleed into each other if decoupling is inadequate. On location, you're fighting three adversaries simultaneously: poor shielding, excessively long cable runs, and faulty ground connections. The insidious part: crosstalk doesn't simply disappear in the edit—you have to eliminate it at the source, otherwise the interference will be in your final mix.
In practice: First, check wireless frequencies. Two systems on adjacent channels? Maintain at least 1 MHz separation, preferably more. Disconnect XLR cables from the power grid—physically, not just in the rack. Use balanced lines, never jack-to-RCA in a professional environment. Is the ground properly connected at the mixer or camera? Ground loops can introduce hum. A cheaply laid USB cable next to the audio line? Welcome to Crosstalk 2.0. For wireless setups, align the antennas perpendicular to each other—this also reduces mutual interference. In video assist or monitors, crosstalk is often more audible than later on set because the signals are passed through undamped.
In the edit, you can address crosstalk with notch filters or noise reduction, but that's always second-rate repair work. It's properly solved on set—through diligence, distance, and compliant cabling. A good sound assistant with clean cabling saves you thousands in editing time and headaches in the mix.