Shotgun Mic Explained
Principle and Design
Shotgun microphones employ an interference tube to achieve a highly directional polar pattern (supercardioid or lobar). The long, slotted tube rejects off‑axis noise by phase‑cancelling sounds arriving from the sides, isolating dialogue or specific environment sounds from a distance.
Shotgun Mic: Technical Specifications
- Length: Longer tubes yield narrower acceptance angles and higher directivity index.
- Polar pattern: Supercardioid or lobar, with typical pickup angles of 15–30°.
- Frequency response: Emphasizes midrange (50 Hz–20 kHz) for speech intelligibility.
Film Production Applications
Boom operators mount shotgun mics on poles, placing them just out of frame to capture actors’ voices clearly. Wireless variants attach to cameras for run‑and‑gun shoots, though they risk handling noise without proper shock mounting.
Shotgun Mic: Best Practices
- Mounting: Use shock mounts and boom dampers to minimize handling noise.
- Wind protection: Employ blimps, foam windscreens, and furry “dead cats” outdoors.
- Positioning: Maintain consistent distance and angle to avoid proximity effect and tonal shifts.
Shotgun Mic: Comparative Overview
| Feature | Lavalier Mic | Shotgun Mic |
|---|---|---|
| Directionality | Omnidirectional/cardioid | Supercardioid/lobar |
| Placement | On talent (clipped) | Boom or camera‑mounted |
| Visibility | Concealed | Visible on boom |
| Ambient Rejection | Moderate | High |
Shotgun Mic: Trivia
- The “shotgun” nickname stems from the tube’s resemblance to a shotgun barrel with slits. - Pioneered by manufacturers like Sennheiser, Rode, and Audio‑Technica, shotgun lengths vary to suit different directivity needs.