When looking at any microphone, we notice some sort of screen that covers the microphone diaphragm and capsule. This screen is typically a mic grille/cap mesh, but can also be a windscreen, and/or an additional pop screen/filter.
Why do microphones have screens? Mics have screens (grilles/caps) in order to physically protect their sensitive diaphragms. Screens also protect against plosives (pop filters) and work to minimize wind noise (windscreens). Perforated screens provide the protection mentioned above while still allowing sound waves to reach the diaphragm.
In this article, we’ll run through the reasons microphones utilize grilles/cap, windscreens, and pop filters.
Why Do Microphones Have Grilles/Caps
The grilles/caps on microphones are designed primarily as a protective shield for the microphone capsule and diaphragm. Of course, these grilles/caps need to be perforated in order to allow sound to actually travel through them and reach the microphone diaphragm.
Microphone diaphragm are sensitive. They need to be in order to effectively pickup the tiny air vibrations caused by sound.
However, this sensitivity also puts microphone diaphragms at risk of physical damage. Ribbon diaphragm, which are the most fragile, have been known to snap simply from dust particles that hit the diaphragm as the mic is being transported.
The grille or cap of a microphone effectively protect the microphone capsule/diaphragm from most external solids, like instruments, lips, the floor, etc.
However, the grille can also help against vocal plosives.
Some microphones, like the Heil PR40, have multiple off-set screens in their grilles that act to reduce the effects of vocal plosives.
Grilles are also used effectively in the design of microphone polar patterns.
In top-address directional microphones, acoustic labyrinths (complete with external grilles) are often used to the rear of microphone capsule in order to allow sound to reach the rear of the diaphragm.
The Shure Unidyne III capsule was the first time to feature this grille design and was brought to market in 1959.
Grilles and slits are also used in the long interference tubes of shotgun microphones. These slits are carefully calculated along the length of tube to cause cancellation of sound waves that enter the tube off-axis.
The first time this interference tube technology entered the market was in 1956. It was introduced in the Lab W (Sennheiser) MD 82 microphone.
The Sennheiser MD 82 and Shure Unidyne III are both features as “microphone firsts” in my article Mic History: Who Invented Each Type Of Microphone And When?
Grilles and acoustic labyrinths can also be positioned in such a way that a directional microphone does not experience the proximity effect, as is the case with the Electro-Voice RE20 and other E-V mics with Variable-D technology.
The Electro-Voice RE20 and the aforementioned Heil PR 40 (as well as the Shure SM58 and Neumann U 87) are featured in my article 50 Best Microphones Of All Time (With Alternate Versions & Clones).
Many microphone grilles have acoustic foam in their interior. This helps to further protect the microphone from plosives and other gusts of air.
For more information on microphone grilles/caps, check out my article What Are Microphone Grilles And Why Are They Important?
For more information on microphone polar patterns, please consider reading my in-depth article The Complete Guide To Microphone Polar Patterns.
Why Do Microphones Use Windscreens
As the name suggests, microphones use windscreens to protect themselves from wind.
The typical sound of wind happens when the wind causes tiny vortexes on solid surfaces. A microphone grille/cap, by itself, will not serve to protect a microphone from wind noise. However, as mentioned before, many grilles have interior acoustic foam which acts sort of like a windscreen.
A windscreen works by having a soft perforated material that:
- Reduces the amount of wind noise due to its softness.
- Absorbs plosive and wind energy.
- Acoustic permeability allows sound waves to pass through with very little affect on frequency.
- Further separate any unavoidable wind noise from the mic capsule.
Microphone windscreens are essential when using microphone outdoors but also play a role in the studio.
Windscreens can help to further reduce plosives in the microphone by absorbing wind energy. This helps the microphone to capture clean vocals (though pop filters are more effective, which we’ll talk about later).
By the same mechanics, windscreens also work to reduce “wind noise” that is caused by moving sources.
The best example to explain what I mean by this is a shaker egg. The shaker egg (pictured) has tiny sand-like particles within it and makes sound as it moves, stops, and moves again back and forth. As we shake a shaker egg, the movement of our arm, hand, and the egg cause movement of air. This air movement can easily overload the mic capsule if we’re too close. That is, unless we’re using windscreens.
So windscreens help to minimize the air movement at the mic capsule, which drastically reduces the amount of noise in the mic signal (if the windscreen is of good quality, of course).
Windscreens are often simple spongy foams that slip directly over a microphone grille/cap. For example, the On-Stage windscreen (link to check the price on Amazon) pictured below simply slips over the grille of microphones like the Shure SM58.
However, these windscreens can also be positioned away from the microphone body. In order to be effective in this case, the windscreen must encompass the entire microphone rather than just the grille/cap and acoustic openings.
Perhaps the most famous windscreen of this type is the Rode Blimp (link to check the price on Amazon), which is pictured below and also features an internal shock-mount for boom microphones:
For more info on external microphone windscreens, check out my article What Are Dead Cats And Why Are Outdoor Microphones Furry?
Why Do Microphones Use Pop Filters
Pop filters are generally used on vocal microphones in the studio.
Microphone pop filters work to eliminate vocal pops and plosives in the microphone signal by dissipating plosive energy before it ever reaches the microphone.
Though grilles, caps, and windscreens will definitely help with plosive protection, it’s often necessary to use a pop filter in professional studio recording to further reduce the likelihood of plosive induced microphone overloading.
Vocal plosives are caused when any part of the vocal tract is closed off momentarily and then opened back up abruptly. This action causes a blast of air to emit from the speaker’s mouth. Plosives, in English, happen on the hard consonants of the following letters:
- B: closing and opening of the lips.
- P: closing and opening of the lips.
- D: closing of the tongue and top of mouth near teeth.
- T: closing of the tongue and top of mouth near teeth.
- G: closing of the tongue and back of mouth/start of throat.
- K: closing of the tongue and back of mouth/start of throat.
Pop filters are made of thin perforated screen-like material. The two main materials are perforated steel mech and nylon.
As plosive energy hits the pop filter screen, it is dissipated. The strong and direct plosive at the front side of the pop filter screen becomes scattered in many different directions and much weaker once it passes through the screen.
Pop filters are positioned some distance away from the microphone body (unlike the typical grille or windscreen). The distance allows the plosive energies to dissipate fully before they have a chance to reach the mic diaphragm.
Check out the following photo to see the Rode NT1-A’s pop-filter position in front of the microphone. This pop filter is actually built into the design of the NT1-A’s basket-style shock-mount.
Note that pop filters do take up space and are not typically used in live sound reinforcement where it’s often critical that the singer/speaker be as close to the microphone as possible (for gain-before-feedback reasons).
For more information on microphone pop filters and plosives, check out the following My New Microphone articles:
• What Is A Microphone Pop Filter And When Should You Use One?
• Top 10 Tips For Eliminating Microphone Pops And Plosives.
Do I need a pop filter for my dynamic microphone? Unless you’re recording vocals with your dynamic microphone, chances are a pop filter will not improve the audio signal by any significant amount. However, when using your dynamic mic for vocals in a relatively quiet environment, a pop filter will improve sound quality by protecting the mic from plosive pops.
For more info on dynamic microphones, check out my article Moving-Coil Dynamic Microphones: The In-Depth Guide.
Why do singers sing so close to the microphone? Singers sing closely to a microphone in order to get the best signal-to-noise ratio they can. By singing in close proximity, a singer’s voice is louder relative to the other, more distant, sounds that the mic also picks up. Singing close also has the added benefit of the proximity effect in directional mics.
For more information on microphone signal-to-noise ratio and the proximity effect, check out the following My New Microphone articles:
• What Is A Good Signal-To-Noise Ratio For A Microphone?
• In-Depth Guide To Microphone Proximity Effect.