A lavalier (also lav, lapel microphone or clip-on microphone) is a miniature microphone worn on the body, usually clipped to clothing near the chest or hidden under fabric, that captures a speaker’s voice at a short and constant distance. Among microphones, it is the standard tool for hands-free speech pickup in television, film, interviews, theater and conference audio.
Most lavaliers are electret condenser microphones with capsules only a few millimeters across. They are connected by a thin cable to a recorder, a camera or, more often, a wireless bodypack transmitter, which gives the speaker full freedom of movement.
How a lavalier microphone works
A lavalier uses the same principle as a larger condenser microphone: sound moves a thin diaphragm in front of a fixed backplate, changing the capacitance between them. In an electret design, the charge is permanently stored in the material, so the capsule needs only a small bias voltage for its built-in impedance converter rather than full 48-volt phantom power.
That bias voltage, often a few volts, is supplied by the wireless transmitter, a battery adapter or a phantom power adapter with an XLR connector. The capsule is tiny, so the microphone is light and unobtrusive, but the small diaphragm also limits its low-frequency sensitivity and raises its self-noise compared with large studio microphones.
Because the microphone sits on the chest rather than in front of the mouth, the signal has a characteristic tonal balance. The chest resonance adds energy in the lower midrange, and the high frequencies of speech, which project forward, are partly shadowed by the chin. Many lavaliers therefore have a built-in presence boost or offer interchangeable caps that shape the high-frequency response.
Key specifications and their typical ranges
Lavalier performance is defined by a small set of specifications. The ranges below describe typical professional models; exact values differ between manufacturers.
| Specification | Typical range | What it affects |
|---|---|---|
| Capsule diameter | About 2 to 6 mm | Concealability and self-noise |
| Self-noise | About 20 to 35 dBA | Hiss in quiet scenes |
| Maximum SPL | About 120 to 140 dB | Handling shouting without distortion |
| Frequency response | About 20 Hz to 20 kHz | Tonal range of speech pickup |
| Sensitivity | About 2 to 20 mV/Pa | Gain needed at the preamplifier |
Connector type matters in practice. Wireless systems use different connectors, such as 3.5 mm locking jacks, TA4F or proprietary plugs, so lavaliers are often bought with the specific termination required by the transmitter.
Polar patterns and lavalier types
The polar pattern decides how forgiving the microphone is about placement. Most lavaliers are omnidirectional, because the angle between mouth and capsule changes constantly as the speaker turns their head.
| Type | Polar pattern | Strength | Typical use |
|---|---|---|---|
| Omnidirectional lavalier | Omni | Consistent tone despite head movement | Film, television, interviews |
| Directional lavalier | Cardioid or supercardioid | Better rejection of loudspeakers | Live sound and conferences |
| Headset microphone | Omni or cardioid | Constant distance to the mouth | Theater, fitness, high-feedback stages |
| Subminiature lavalier | Omni | Hidden in hairlines or costumes | Drama and musical theater |
Directional lavaliers offer more gain before feedback on a live stage, but they demand precise aiming and suffer from off-axis coloration when the speaker turns. For recorded dialogue, the omni design is almost always the safer choice.
How a lavalier compares with other microphone choices
The lavalier competes mainly with the shotgun microphone on a boom and with handheld dynamic microphones. Each choice balances sound quality, visibility and freedom of movement differently.
| Microphone | Distance to mouth | Sound character | Main limitation |
|---|---|---|---|
| Lavalier | About 15 to 25 cm, constant | Close and dry, chest coloration | Clothing noise |
| Shotgun on boom | About 0.5 to 1 m, variable | Natural and open | Needs an operator and space |
| Handheld dynamic | A few centimeters | Strong and proximate | Visible and occupies a hand |
| Headset | A few centimeters, constant | Very consistent | Clearly visible |
In film production, the two are often recorded together: the boom gives a natural perspective, and the lavalier serves as a safety track for wide shots or noisy locations.
Placement, concealment and common problems
Correct placement is the largest single factor in lavalier sound quality. A position on the sternum, about a hand’s width below the chin, usually gives the best balance between clarity and natural tone.
- Clothing rustle: fabric rubbing on the capsule is the most common problem; secure the cable and use a mount or tape to isolate the capsule.
- Muffled sound under clothing: thick fabrics absorb high frequencies; choose thin layers and compensate with equalization.
- Placing it too high: a capsule at the collar sounds boomy from the throat and is shadowed by the chin.
- Wind noise outdoors: use a foam or fur windscreen, or hide the capsule beneath a protective layer.
- Cable strain: a strain-relief loop near the clip prevents the cable from pulling on the capsule and transmitting noise.
In concealed placement, sound mixers often use adhesive mounts, small fabric covers or windscreens designed for hiding the capsule under a shirt, while the cable is routed and taped along the body to the transmitter.
A non-technical view
A lavalier is the tiny microphone clipped to a shirt that people wear on television or on stage. It stays close to the speaker’s mouth all the time. Their voice therefore sounds clear and steady, even when they walk around or turn their head.
The microphone sends the voice through a thin wire, usually to a small transmitter on the belt. Nobody needs to hold anything, and it can even be hidden under clothing so viewers do not see it.
A concrete example
A documentary crew films a park ranger walking along a busy forest trail. A boom operator cannot follow her through the trees, and passing hikers make the ambient noise uneven. The sound recordist fits an omnidirectional lavalier on her sternum, hidden under a thin outer shirt with an adhesive mount and a small fabric cover.
The cable is taped to her back and connected to a wireless transmitter on her belt. The recordist sets the gain so that normal speech peaks around -20 dBFS with headroom for exclamations, and records the boom as a second channel when possible. In editing, the lavalier track provides clear and consistent dialogue for every walking shot, and only light equalization is needed to reduce the chest resonance.