What Is an Omnidirectional Microphone? Pattern and Uses

An omnidirectional microphone picks up sound roughly equally from every direction. Its pickup pattern has a coverage of 360 degrees, so sound from the front, sides, back, above or below is captured at a similar level. Directional types work differently: cardioid and shotgun microphones favor sound from one side and reduce sound from the others.

Before you start

The pickup pattern is a physical property of the microphone capsule and housing. No software setting can turn a fixed directional microphone into an omnidirectional one. The exception is a multi-pattern microphone, which can switch between patterns with a hardware selector or the manufacturer's own control software. Check the manual to see whether your model can do this.

Reading the omnidirectional polar pattern

A polar pattern diagram shows how sensitive a microphone is to sound arriving from each angle. The microphone sits at the center, 0 degrees is the front, and the rings mark sensitivity levels. An omnidirectional diagram is close to a full circle, which means sensitivity is about the same all the way around. Real omnidirectional microphones usually become somewhat more directional at higher frequencies, so spec sheets often draw several frequency curves on one diagram. Omnidirectional capsules also do not have the bass boost that directional microphones produce when used very close to the mouth, known as the proximity effect.

Typical uses and examples

• Lavalier (clip-on) microphones worn on clothing, where the angle to the mouth changes as the speaker moves.
• Conference and boundary microphones placed on a table for several people.
• Recording room ambience, choirs or ensembles where a natural room sound is wanted.
• Measurement microphones used for acoustic testing.
• Interviews where one microphone is held or placed between two people.

What you need

• The microphone's spec sheet or manual, which states its polar pattern.
• The correct connection for your microphone: USB, a 3.5 mm jack, or XLR through an audio interface.
• The recording or video call app you plan to use.
• A clear idea of where processing happens. Input selection, input level and pattern switching are local settings. Noise suppression, recording and storage in a call or cloud app may be handled by that service, so check its privacy and file handling documentation instead of assuming.

Step-by-step instructions

• Confirm the pattern. Look for omnidirectional or omni in the specifications. On a multi-pattern microphone, set the selector to the omni position. This position is commonly marked with a circle icon, but check the manual to be sure.
• Note your current settings, including the selected input device, input level and sample rate, so you can restore them later.
• Connect the microphone and select it as the input device in your operating system's sound settings. Select it again inside your app, because many apps keep their own device choice. Do not confuse it with the output device, which is your speakers or headphones.
• If your device or app lets you set a sample rate, use the same rate in both places. 48 kHz is common for video and calls, and 44.1 kHz is common for music.
• Position the microphone by distance rather than direction. It hears every side equally, so moving it closer to the speaker is what makes the voice louder than the room. Clip a lavalier to the chest, away from fabric that can rub against it. Place a table microphone centrally between the speakers.
• Set the input level. Speak at your normal volume and adjust the gain until the loudest peaks stay well below the clipping point on the meter. If the app has automatic gain control and you want a steady level, consider turning it off.
• For calls, wear headphones. An omnidirectional microphone easily picks up sound from your speakers and sends it back to the other people on the call as echo.

Check the output

Record a short test in the app and room you will actually use. Speak from the front, then from the side and from behind the microphone. With an omnidirectional pattern, the level should stay similar in every position. If the level drops sharply from behind, the microphone is directional or is set to another pattern.

Listen to the test on headphones. Check for room echo, hum, and background noise in the silent gaps, and make sure the meter never reached clipping. To confirm the file format and sample rate, look at the app's export settings or the file's properties. A recording cannot exceed what the device and app support. Audio sent through a call service may also sound different from a local recording of the same input.

Common problems and next steps

• Too much background noise or room echo: this is expected, because the pattern picks up the whole room. Move the microphone closer to the speaker, lower the gain, add soft furnishings, or switch to a cardioid pattern if your microphone has one. App noise suppression can also help, but first check where that processing takes place.
• Other call participants hear an echo: use headphones, and turn on echo cancellation if your app offers it.
• The microphone is not detected or the wrong one is used: select the input device again in both the system settings and the app, reconnect the cable, and check that the app has microphone permission in your system's privacy settings.
• The level is too low or too high: adjust the input level, and check whether automatic gain control is changing it.
• Crackling, distortion or the wrong pitch: check for a sample rate mismatch and set the device and app to the same rate.
• The sound is dull from some angles: higher frequencies can still be slightly directional, so point the front of the microphone roughly toward the main source.
• If one voice needs to stand out in a noisy space, an omnidirectional microphone may be the wrong choice. A directional microphone placed close to the speaker will usually reject more of the room.