Lavalier microphone

A lavalier, or lav, is a miniature microphone clipped to clothing and wired to a bodypack transmitter. It exists because it disappears: on camera and from the back of a ballroom, it is the microphone nobody notices.

Placement is the whole job. The target is high on the chest, roughly a hand’s width below the chin and on the centre line, so the voice arrives from directly above. Move it down and the voice goes chesty and dull. Move it to the side and the level drops every time the speaker turns their head towards the screen behind them — which, in a general session, is constantly.

What goes wrong is almost always clothing rather than electronics. A lav under a scarf, against a necklace, behind a lanyard or clipped to a loose jacket lapel will rustle, and the rustle is louder than the voice. Hair, collars and hard-shelled badges do the same.

A lavalier also gives away a fixed amount of level before feedback, because it is a long way from the mouth compared with a headset. For a panel seated at a table it is the right choice. For a presenter walking a stage in front of a loud system, a headset will go considerably louder before anything rings, and the trade is that it is visible.

Corporate event production — owned inventory, our own crew, and a site survey before anything is specified.

• Headset microphone A microphone on a thin boom worn over the ear, held an inch or two from the mouth — visibly there, and worth roughly ten decibels of extra level before the system rings.
• Wireless microphone A microphone with a radio transmitter instead of a cable — legal in a narrower slice of spectrum than most people assume, and not something to buy by channel count alone.
• Gain structure Setting the level at each stage of the signal chain so the system runs well above its noise and well below its ceiling — the thing that is wrong when a mix sounds thin, noisy or brittle.