How Does a Noise Cancelling Microphone Work in an Industrial Noisy Environment?

When recording in a environment that is noisy using a microphone that can reject ambient noises is key to making sure your recordings are clean and clear. The way that a noise canceling microphone works can vary depending on its design and the type of ambient sound it's trying to filter out. Understanding how it works will help you find a mic that's perfect for your needs.

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Active Noise Cancellation

Active noise canceling (ANC) technology neutralizes ambient sounds by adding a sound that is second is designed to cancel the first. This sound is produced by microphones that listen to external sounds and generate a phase-inverted signal that effectively blocks them out.

In an industrial noisy environment, ANC is great for protecting workers from hearing things they shouldn’t or getting distracted by loud noises that could cause accidents. It also allows crews to easily communicate more so they can do their job safely and efficiently.

ANC is used in headphones and earbuds for this purpose. It works by incorporating handset with high quality microphones into the headphones that listen to outside sounds and generate a phase-inverted sound that effectively blocks them out.

Adaptive ANC uses onboard microphones that are designed to adjust the strength of the cancellation based on the level and type of background noise. This method can be better than feedforward ANC, which only uses external microphones for noise sensitivity, or feedback ANC, which is sensitive to short-burst high-frequency sounds that could get amplified.

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Passive Noise Cancellation

Passive noise canceling microphones work by blocking sound that is ambient entering the ear canal. This can be accomplished through physical features like shape, design and materials used in the headset or earbuds.

Sound is a pressure wave that consists of alternating periods of compression and rarefaction (or peaks and troughs). When two waves with the amplitude that is same opposite phases (antiphase) collide, they cancel each other out, also known as destructive interference.

Noise-canceling headphones work in a similar way. They use a tiny microphone and PTT handset on the outside of the headphone to monitor surrounding noise, then 'anti-noise' the sound.

A passive noise-canceling headset will typically have padding or foam on the ear cups that act as a physical barrier to prevent ambient sound from entering your ears. How effective this noise cancellation will be depends on how well it fits and the acoustic design of the headset itself, which is why headsets that have earbud-style or in-ear designs are generally considered to be better passive noise canceling headphones.

Microphone Design

A microphone design needs to work hard to prevent unwanted sounds from getting through in an industrial noisy environme. Often, these unwanted sounds can come from small movements or air rushing over the microphone.

A noise canceling microphone is designed to minimize these unwanted sound waves by electronically reducing them. This helps you stay focused on what you need to do, and gives your callers a clear signal so they can hear you clearly.

One way to do this is by incorporating time delay networks between the front and ports that are rear. This means it takes nearly 40 microseconds for a wave that is sound travel 13 mm from the rear to the front port and vice versa.

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Microphone Pickup Pattern

When recording audio, it is crucial to understand microphone pickup patterns. These patterns describe how a microphone picks up and rejects sound in different directions around it.

The most common directional pattern is cardioid, which reduces the level of pickup from the sides and rear while focusing on a single sound source. This is a good choice for live music or interviews where the focus is on one person speaking directly to the audience.

Supercardioid microphones are similar to cardioid mics, but increase the sensitivity from the front and exclude more sound from the  sides and back. These are a option that is good recording dialogue, especially when used in shotgun mics.

The subcardioid microphone polar pattern is the middle ground between omnidirectional and cardioid, picking up a wide range of sound from the front, gradually reducing towards the rear. It is a good choice for stage use and professional studios with acoustics that aren’t too harsh.