If you've worked on a film set or have seen pictures of work being done, you may have asked yourself why the microphone is covered in fur. What is that dead cat (yes, “deadcat” is an actual industry term) doing at the end of that boom pole?
So what are dead cats, and why are outdoor microphones furry? The “furry” part of a microphone is an optional windscreen and is commonly referred to as a “dead cat” or “windjammer.” Dead cats are designed for outdoor use, providing an extra layer of protection from wind noise and plosive sounds while remaining as acoustically transparent as possible.
A dead cat is also quite the attention grabber! Let's discuss these furry windscreens in more detail in this article.
To learn about my recommended microphone dead cats, check out My New Microphone's Best Microphone Windscreens.
What Are Dead Cats And Why Are Outdoor Microphones Furry?
Dead cats. That's quite the terminology to use when referring to a fluffy windscreen. However, it's commonly accepted terminology in the audio and film industries. So what is a deadcat?
Rode, from Australia, calls them “dead wombats.”
A dead cat is an effective microphone windscreen. Unlike most plain windscreens, dead cats feature fake “fur” to further reduce wind noise pickup in the microphone. These windscreens are frequently utilized in outdoor recordings. This is why many microphones we see outdoors are furry!
Let's talk about the two common types of dead cats we'll come across in audio recording. These two types are generally referred to as “dead cat” and “dead kitten” (no, I'm not kidding!).
The Dead Cat And The Zeppelin/Blimp Windscreen
This is typically what people envision when they think “furry microphone.”
The dead cat is basically a furry sock that fits over a zeppelin windscreen. These removable fur windscreens provide an extra layer of wind noise reduction to the already effective blimp-style windscreen.
When I'm operating the boom microphone for film shoots, I use the zeppelin-style windscreen whenever possible. When outdoors, I put the dead cat on. When indoors for extended periods of time, I like to remove the dead cat. This decision is based mostly on courtesy for the talent (those being filmed) since fur strands sometimes fall off when swinging a boom pole around.
For more information on boom microphones, check out my article How To Properly Hold A Boom Pole And Microphone.
The zeppelin/blimp windscreens excel at reducing microphone noise for many reasons:
- Provide a windscreen for the microphone from all directions
- Provide a shock mount (typically Rycote Lyre styled) for the microphone
- Provide space between the turbulent surfaces (outer case) and the microphone
The relatively hard surface of the blimp windscreen is a turbulent surface for wind noise to happen. The dead cat supplies a soft surface to absorb wind energy and produce quiet “mini-turbulences.” The combination of a quality zeppelin windscreen and the dead cat does an excellent job of reducing wind noise!
The Dead Kitten And The Bare Microphone
The dead kitten is a smaller type of dead cat that slips right onto the microphone itself. Dead kittens are also commonly referred to as windjammers. Let's use this more humane term for the rest of the explanation.
Windjammers are typically made of both synthetic fur and acoustic foam. The idea, of course, is to improve upon the typical foam windscreen by adding an extra layer of wind noise protection.
You'll often see windjammers on-camera microphones rather than at the end of boom poles.
Although not as effective at reducing wind noise as the zeppelin/dead cat combo, the windjammer does a great job at reducing wind noise (and certainly a better job than acoustic foam by itself).
A Note On Acoustic Transparency
It's essential that dead cats remain acoustically transparent. Make sure to check the spec of any dead cat you buy, ensuring the product you purchase is acoustically transparent (don't worry, most are!)
How Does Wind Affect A Microphone Signal?
When recording audio in the great outdoors, wind can be our worst enemy. Not only does it have the potential to blow over our equipment, but it can really ruin an otherwise great audio signal.
There are basically 2 ways that wind will negatively impact a microphone's signal:
Let's talk about how dead cats address these two critical issues.
Gusts At The Microphone Diaphragm
This is the direct noise a microphone will pick up due to the wind.
Gusts of air reach a microphone diaphragm similarly to sound waves and cause unwanted and prolonged noise.
Diaphragms are designed to sense the subtle changes in sound wave pressure differences. A gust of air hitting the diaphragm causes a pressure difference between the front and back of the diaphragm and, therefore, a large peak in the microphone signal.
This peak is often elongated and creates unwanted noise in the lower frequencies. It also has the potential to overload the microphone preamplifier.
It goes without saying that if we're getting wind noise in the microphone signal, we're not capturing the audio we want. The wind is basically gusts of air, so we need to protect the microphone capsule from wind to achieve the best sound possible.
Let's look at our options for reducing wind:
Pop filters effectively reduce vocal plosives in studio settings but don't stand a chance against the wind. Common materials for pop filters include perforated metal and fabrics such as woven nylon.
Pop filters and windscreens reduce plosive energy by effectively dissipating the blasts of air that pass through their membranes. The gusts of air (whether that be wind or vocal plosives) hit the filter/screen full force with a strong sense of direction, and as they pass through, their force is weakened, and their direction is scattered.
To learn more about pop filters and plosives, check out my articles What Is A Microphone Pop Filter And When Should You Use One?, Best Microphone Pop Filters and Top 10 Tips For Eliminating Microphone Pops And Plosives.
Windscreens do a great job of surrounding a microphone capsule, thereby reducing the strength of wind gusts hitting the microphone capsule. Slip-on windscreens are often made from acoustic polyester foam. Some windscreens have more complex designs (such as the zeppelin or blimp), including a plastic skeleton that hosts a fabric screen.
Dead cats take things one step further (no pun intended). The fur on the dead cat adds an extra layer of protection. The furry part is typically on the outside of a typical windscreen. The dead cat effectively dissipates gusts of wind before they hit the inside windscreen. This extra dissipation step works very well at reducing wind noise!
For more information on reducing microphone noise, check out my article 15 Ways To Effectively Reduce Microphone Noise.
Turbulence At A Physical Surface Near The Microphone
This is the indirect noise a microphone will pick up due to the wind.
Does wind make noise if it doesn't hit objects?
The short answer is no. Wind noise is actually caused by air hitting a surface. The turbulence caused by wind at a surface is the source of all wind noise. The most common surface people hear wind noise against is the surface of their ears.
The fur of the dead cat acts as a sort of absorptive, moveable surface. As wind contacts the fur, the fur moves, absorbing some of the wind energy. This sort of “moving surface” doesn't cause nearly as much turbulence as a hard, stationary surface.
The other critical factor worth noting is the surface itself. Typical windscreens have a solid piece of perforated metal, acoustic foam, or woven nylon. The dead cat has many strands of soft fur. The surface area is much greater and much more flexible. These strands of fur essentially produce micro-turbulence and absorb energy silently.
So long as the dead cat is not matted by wind or rain, it will work effectively. Of course, if the fur is slick against the microphone or the outside of its windscreen, it won't be very successful at reducing wind noise.
An Extra Note On Wind Noise
This piece of information may seem obvious, but it is critical in dead cat application: The further a wind noise is from a microphone, the less that microphone will pick up that wind noise. For this reason, the zeppelin or blimp style windscreen complete with the dead cat has risen to such popularity in outdoor audio recording.
Why is there spongy foam in my microphone? Acoustic foam in a microphone acts as acoustic dampening and as a subtle windscreen. Acoustic foam outside of the mic or in front of the diaphragm acts as a windscreen. The foam in the mic capsule provides acoustic dampening and is critical in the design of the polar pattern and frequency response.
What is the job of an audio boom operator on a film set? Audio boom operators are responsible for capturing audio from the subject without being in the frame. This is typically done with a microphone at the end of a boom pole. The boom op holds the mic just out of the frame and points it at the subject. The boom op may also be the one recording the audio.
Choosing the right microphone(s) for your applications and budget can be a challenging task. For this reason, I've created My New Microphone's Comprehensive Microphone Buyer's Guide. Check it out for help in determining your next microphone purchase.