Lav & Wireless Mics
When the boom can't get close — a wide shot, a moving actor, two people far apart — the lavalier saves the day. A tiny mic hidden on the body, always inches from the mouth. Lavs are a superpower, but they come with two enemies: clothing rustle and wireless dropouts. Beat those and you can mic anything.
The lavalier's whole advantage is proximity that never wavers: because it's fixed to the actor an inch or two from the mouth, it delivers a strong, consistent level no matter how they move or where the camera is. That makes it indispensable for wide shots where a boom would be in frame, for actors who walk and turn, for scenes with people too far apart to boom both, and as a reliable backup track running alongside the boom. The catch is that hiding a mic on a moving human body and sending its signal wirelessly introduces two very specific problems — and most of lav technique is about defeating them.
Enemy #1: clothing rustle (and how to hide a lav)
The lav's signature failure is rustle — the scratchy roar of fabric brushing against the mic capsule as the actor moves or breathes. A lav is only as good as it's rigged, and rigging it well is a real craft:
- Position high and central. The sternum, the center of the chest, or hidden in a collar or tie — close to the mouth and on a relatively stable part of the body. Higher is generally better for clarity.
- Isolate it from fabric. Use the little foam covers, mounting clips, and tape triangles ("bra tape" and specialist mounts) that hold the capsule away from cloth so nothing brushes it. This is where rustle is won or lost.
- Anchor the cable. Loop and tape the wire so it can't tug the capsule when the actor moves — a "strain relief" loop. Cable tension transmits straight into the mic.
- Mind the wardrobe. Stiff, noisy fabrics (nylon, leather, starched cotton) are rustle machines. Coordinate with wardrobe; sometimes a costume choice is a sound choice.
- Test before you shoot. Have the actor move as they will in the scene while you listen on headphones. Catch the rustle in rehearsal, not in the edit.
Enemy #2: wireless dropouts
Most lavs on set are wireless — a bodypack transmitter on the actor sends to a receiver at the recorder — which is what lets the actor move freely. But radio can fail, and the failures are ugly: dropouts (the signal cuts out, leaving silence or static), interference from other devices, and dead batteries mid-take. Defending against them is mostly discipline: keep the transmitter and receiver within reliable range and line of sight where possible; watch for interference from Wi-Fi, phones, and other transmitters and change frequencies if you hear trouble; and religiously monitor battery levels, because wireless packs die without warning and a dead pack is a dead take. And here's the crucial safety net that ties the whole module together: a good lav records to the recorder, but the smart move is to also let the bodypack record internally to its own memory as a backup (many do), or to run the boom simultaneously — so a wireless dropout never means a lost line. Belt and braces. Used well, a hidden lav is invisible and bulletproof; the audience never knows it's there, and neither does a dropout, because you had a backup.
Never trust a single wireless lav with a line you can't reshoot. Radio drops out, batteries die, packs glitch — it will happen eventually, always at the worst moment. So I build redundancy in: I run the boom and the lavs together whenever I can, so if the lav drops, the boom caught it, and vice versa. And I set actor bodypacks to record internally as their own backup where the gear allows. It feels like overkill until the day a wireless craps out on the perfect take and you calmly reach for the backup track that was quietly rolling the whole time.
Plan your sound in the Filmmaker Toolbox — gear checklists, per-scene mic plans, and sound reports for post — so you capture clean audio on set and hand it off cleanly to the edit.