A reflection filter is a device that is used to absorb sound that reflects off the walls in a recording room when audio is recorded.
When a recordist speaks into a mic, their voice is not the only audio that is caught by the unit. Background noise and reflected sound also make their way to the mic.
When you speak into a mic, your voice is reflected off the many surfaces in the room.
The walls, ceilings, doors, and any other surfaces present in the room may cause the sound that’s recorded to ricochet.
That sound is caught by the mic with a bit of delay. This noise lowers the quality of your recording and creates an echo in it.
A reflection filter is used to block the reflected sound from getting to the mic. It is placed in front of the mic, and it filters out any unwanted sounds.
But some might say that a reflection filter may not be too useful. That might be true in some cases, depending on the pattern of sound pickup used by your mic.
The higher quality your microphone is though, the more sensitive it probably is to background noise and other unwanted sounds.
For high-quality recordings, a reflection is not only useful, but it is also essential.
Mic picking patterns
A mic can pick up sound from different directions. It can pick up audio from all the directions around it, or just the front and back or only from the front of the mic.
- Omni: In this pattern, a mic picks up sound from every direction.
- Figure of 8: This means that the mic in use picks up sound from the front and the back of it.
- Cardioid: This is the most commonly used style of sound pickup in mics. It catches sound from just the front of the mic, a bit from the nearby sides.
Which mic you use influences the efficacy of installing a reflection filter.
Since it is placed around the back of the mic (in the opposite direction from where the sound recordist is standing), a cardioid patterned mic would practically render a reflection mic useless.
Because when the sound is not being absorbed from the back of the mic, it’s not going to catch the reflected sound either.
However, if you have a figure of 8 mic then a reflection filter would make a difference by filtering out the reflected noise.
How do you set up a reflection filter?
A reflection filter takes up the entire space around the mic except for the area where the recordist is located.
So what you do to set a reflection filter is you place it behind the back of the mic. The front and back may be different in different mics.
You need to put the filter in the space where the recordist isn’t. It could either be the front or the back, depending on your mic.
- Most reflection filters come with a steel tube that wedges into the rod holding up the mic.
- You can lock the filter in place by rotating the lever at the side.
- However, if the reflection filter you have is not that simple and you are having trouble finding the tying ends, then use the instruction manual.
- The only thing to keep in mind when installing a reflection filter is that you need to cover the entire area around the mic except where the recordist is situated.
- At times you can even mount it on a tabletop if you are using a tabletop microphone.
What does a sound shield do?
A sound shield is a professional sound reflection filter that shields a mic from absorbing reverb sounds.
It comprises of three sound-absorbing walls.
Out of those three, two are foldable while three remain stationary. Acoustic panels cover up those walls that filter out distracting audible artifacts.
You either fix a sound shield through an insert tube around the mic or place it around it on a surface.
It is quite a convenient way to avoid echo in your audio, but it is more effective if you use it along with a pop filter.
How much is an average reflection filter?
You can get a portable reflection filter, just like any other sound equipment, of varying qualities.
You can get it for as low as 75$ or as high as 300$ depending o your budget.
If you can afford an expensive filter unit, there are several options available for you. They range from 200$ to 300-400$.
But if you don’t want to spend a fortune on it, then a 75$ piece would work just fine for you. But then the quality may suffer a bit.
And if you don’t want to buy a reflection filter because you are not sure if you need it, then you can make one at home.
How to build a DIY reflection filter?
There are many ways to build a reflection filter. You can quickly put together a reflection filter by buying only a few supplies from any craft store.
The things you’ll need.
- A cardboard box: It is going to provide structure to your DIY reflection filter.
- Styrofoam sheets and tubes
- Sponge panels
- Glue or double-sided glue
Where to start?
First, cut out the cardboard box into a mini closet or cabinet shaped structure. It should have a backside and four trapezoid style sides. These sides would act as the walls of your reflection filter.
Next, take the Styrofoam tube and paste it on the edges of the cardboard closet that you have created.
It deflects any incoming reverb sounds from the corners of the make-shift filter unit.
Lastly, take the sponge panels and paste them on to the make-do walls of your semi-constructed structure.
They absorb all the reflected sounds from the surrounding from getting into your recording.
Once you have created the DIY reflection filter, you can place your tabletop mic inside it.
But if you are using a standing mic, then you need to create a different kind of reflection filter.
In case of a standing setup, the things you’ll need.
- A wireframe: Get a thick metal wire to build a u-shape frame.
- A chicken wire ply
- Acoustic foam
- Binding wire
- A set of pliers
- A mic stand
How to put everything together?
Make a u-shaped structure with a thick metal wire. And join the wire ends by overlapping below the structure.
- Cover the frame (that you have created with the metal wire) with the chicken wire. Leave some extra bit of the chicken wire sheet so that it can overlap over the corners on the wire structure.
- Use small cutouts of the binding wire to tie together the metal frame and chicken wire at the edges.
- Spread full sheets of foam on the inside (inner curve) of the chicken wire sheet that’s filled up the space of the frame.
- Make sure there are no gaps between the foam sheets. Use small u-shaped cutouts of the binding wire to hold the foam in place. Pass the ends of the u-shaped through the foam and the chicken sheet and cross them over the metal frame.
- Tie together the foam and the frame at 4-5 points to ensure structural stability.
- Now use the ends of the metal wire (that are overlapped to hold the entire structure together) to attach the filter to the mic stand.
- For aesthetics (optional): To personalize your filter, you can cover the backside with a fabric or any other sheet. Secure it in place by tying with the binding wire to the metal frame. You can further decorate it by drawing musical notes or quotes on it if you wish to.
If you don’t have an acoustically treated room to record in, then just a reflection filter is not going to be enough to filter out any unnecessary sounds.
You should also install a pop filter near your mouth to catch all the reverb sounds from getting into the recording from that direction.
Furthermore, try to make your room soundproof. Install acoustic panels to do so, or you can even hang quilts and duvets while recording.
And if you have a walk-in closet, then you can make use of that space too for recording. It can be your temporary yet ever-ready recording room.
Now that you know everything there is to know about a reflection filter, you can easily decide whether or not you want one.
And if you want one but dot want to spend money, then we have also shared with you ways to DIY a reflection filter without hassle.
Have fun recording!