Killing Extraneous Noise When Using a Microphone
Killing unwanted noises when using a microphone requires the knowledge and skill to know the type of noise and have the available tools to suppress it. Here’s a guide to the basics of removing noise when using microphones for recording.
First, it’s important to understand the difference between windscreens and pop filters. Each is designed to suppress a different kind of noise that can ruin a recording. Windscreens are for the suppression of wind or breath noise interfering with the sound recording. A pop filter is specifically designed to block the “p” or “b” sound of the human voice. They can be used separately or together. Since their functions are similar, users often confuse them.
Let’s take windscreens first. Wind noise can come from real outdoor wind or indoor blasts from the breath or vocal plosives. Windscreens are usually made from a block of foam and are designed to fit snugly over the microphone element casing. Some mics incorporate an internal windscreen inside the grill to protect the microphone element.
This level of wind protection is just a minimal beginning. Foam only works with gusts up to nine miles per hour and is mostly used indoors where drafts of air can cause noise. Since most mics come with these foam wind screens, they are the most common.
Most professional sound recordists, however, outfit their mics with a far higher level of wind protection. A step up is Rycote’s “Softie,” which adds an additional layer of wind buffering to the foam. Softies are a low-cost alternative for budget-minded users, but don’t use them in high wind conditions.
For professional recordists, blimp or zeppelin systems offer the highest level of wind protection available. Blimps are complete systems with mounting hardware, an external casing and exterior wind buffering fur. Instead of layering foam and other materials directly on the microphone itself, blimps create an open chamber of space around the microphone.
Even in high-wind situations, the microphone sits in a chamber with still air around it. The outside layer of the blimp is often long synthetic hair used to diffuse wind. The walls of the exterior of the blimp are made of a tight mesh material to further diffuse the rushing air.
These systems are versatile because users can remove the exterior fur, or even the blimp's casing when they're not needed. The interior is hollow, and the microphone resides in the center on an internal shock mount.
High-end wind protection systems are made by companies like Rycote, whose screens range from $100 for basic screens to full scale kits for specific microphones in excess of $1,000. Also, DPA Windpac, WindTech and Rode make excellent high-end wind protection systems.
These complete systems are designed for situations in which maximum isolation from wind and handling noise is required for professional use. Sometimes the wind protection technology can be more expensive than the microphone being protected.
One consideration with major wind protection is that all the material combined can dampen higher frequencies. Some microphones build in compensation for windscreens, though most don’t.
For example, Rode’s Stereo Videomic X has a +6 dB high frequency boost switch which is recommended when using the mic’s included outdoor synthetic fur wind shield. Rode suggests engaging the high frequency boost to combat the slight loss of high frequency detail experienced when covering the mic’s capsule.
Pop filters, on the other hand, are designed mainly to reduce excessive plosives such as “p” and “b” sounds. Many pop filters are built into microphones. Perhaps one of the most famous is Shure’s SM58, a mainstay of musicians because of its tailored vocal response and built-in filter.
The Shure mic incorporates a highly effective, built-in spherical filter with a steel outer mesh that minimizes both wind and breath "pop" noise. A cardioid pickup pattern isolates the main sound source while minimizing unwanted background noise.
For studio microphones used for vocals, a pop filter is usually placed between the singer and several inches in front of the mic. The screen is used to block the vocal artifacts and allow the voice to pass through the filter unobstructed and uncolored.
Though there are hundreds of low-cost pop filters available, one of the best professional designs is the Stedman Proscreen XL, an advanced filter that offers a six-inch diameter screen surrounded by ultra-fine rubber that does not interfere with vocal recording sound quality. A 13-inch heavy-duty adjustable gooseneck with an extended clamp holds the filter firmly in place.
The Proscreen pop filter is far more effective than cheaper fabric filters. Instead of simply diffusing bursts, it redirects airflow downward away from the microphone capsule. The gooseneck is covered with a heavy duty vinyl shrink material keeping the gooseneck protected and offers lower noise while adjustments are made.
As with virtually all aspects of pro audio, you get what you pay for. Yes, there are plenty of cheap options, but most don’t work so well when real-life environmental problems occur. If you are doing pro audio for a living, it’s a proven fact that having the best tools pay off again, again and again.
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