In part one of this series on DIY acoustic treatment for recording vocals and voice I covered basic room acoustics, room position and reverb.
Now in part two you'll use that knowledge to place acoustic treatment in your recording room using stuff lying around your home.
Here is a voice recording in an untreated room with a lot of hard surfaces:
Here is a voice recording in a room with DIY acoustic treatment. I’ll teach you exactly how to achieve this sound in this tutorial:
Notice how the treated example is more intelligible and pleasant sounding. This is what you want to achieve.
Where to Place the Treatment
Before I explain the various materials and objects that you can use as treatment, you need to know where to put everything.
The primary place to put treatment is behind your head—especially if you are using a cardioid microphone.
If you are recording at home, I recommend you use a cardioid mic in all situations. If you are recording in a treated room, an omnidirectional mic might sound better.
Since you’re reading this article about DIY acoustic treatment, I’ll assume you are recording at home or in an untreated room. In which case—grab a cardioid mic.
As the microphone is pointing towards your head, to record your voice, it will be more sensitive to sound behind your head than anywhere else.
For this reason, reflections from a wall behind you will be picked up the most by the microphone. Putting treatment behind your head will have the biggest impact on your recording.
The next place you put treatment should be behind the microphone. Take a look at this image of a cardioid polar pattern:
Note the small area behind the microphone. The mic is more sensitive to sounds behind it than to the sides.
Now imagine you are facing a microphone and singing or talking into it. More volume comes directly from your mouth than anywhere else. Those sound waves are captured by the microphone but then continue to bounce of the wall or a surface behind the mic. They then reflect back into the microphone.
These reflections will be louder than any others because of the direction of your voice. Put some treatment behind the mic to reduce the volume of these reflections.
After that the best place to put treatment is to the side of the microphone. This will reduce the volume of reflections from the side walls.
Your final option is to place treatment above or below yourself and the microphone. If you have a carpet, try sitting on the floor. This will put you further from the hard, reflective ceiling and closer to the more absorptive floor.
You can also suspend treatment above your head or lay treatment on the floor if you have wooden flooring.
How To Build Your DIY Vocal Booth
There are loads of materials you could use as treatment. The more absorptive, the better. The thicker, the better.
If it would absorb and retain lots of water it will probably do the same with audio (with the exception of towels—they are too thin.
Perform what I like to call the shout test. Put your face right up the material and shout into it. The quieter your shout is, the better. You may get some funny looks but it’s all in the name of science.
Here are a few ideas to get you started. All of them are completely free if you have a normal bed.
Mattresses are the best DIY absorbers to use. Due to their size they absorb more low frequencies than anything else in your home. Although it is inconvenient, you will notice an instant difference.
You could use several mattresses—behind and to the sides of the mic—to create an enclosed vocal booth. Be careful of making the sound too dead though.
Duvets can also be highly effective. Use a clothes airer, an ironing board or a chair to suspend the duvet and position it.
For a quick but sweaty option, get under the duvet in your bed. The mattress and the duvet combined means very little reverb. Having the duvet over your head also stops reflections from the ceiling.
Not quite as effective as duvets, but another great option.
A great option for behind and to the side of the mic if you are recording at a desk. You can rest the pillows horizontally and stack them for better absorption!
Open the Closet
I wouldn’t recommend actually getting in your closet—the door will be highly reflective and close to the microphone. But opening the door to your wardrobe and using it as absorption behind your head or behind the mic is a quick and convenient option.
Line a Box With Pillows
This is essentially a free DIY version of a reflection shield, which are designed to reduce reflections from the rear and sides of the mic.
Use some tape to attach pillows or blankets to the inside of a large box and put the microphone inside facing out.
- Build an Effective Room Treatment on the CheapBobby Owsinski20 Aug 2009
- Beginner's Guide to Acoustic TreatmentMo Volans06 Apr 2009
Affordable Paid Alternatives
If you want to spend a bit of money you can create some more permanent and convenient. It’s not ideal tearing apart your bed every time you want to record.
DIY Reflection Shield
You can quite easily build your own reflection shield using acoustic foam,which is cheap, and a wire frame.
You could also apply the ‘absorption in a box’ concept with acoustic foam to create a Port-Booth.
You could also use two small DIY acoustic panels to create a reflection shield.
DIY Acoustic Panels
You will get the best absorption with DIY acoustic panels that use proper acoustic insulation material. They’re cheap to build but require quite a bit of effort. It took me three days to plan and build ten panels for my home studio.
As well as putting them on the wall you can suspend them on microphone stands to create a movable absorption panel. Position one directly behind your head for impressive results.
With a basic knowledge of acoustics, you can now consider the room you are recording in and your recording position. This is the first step to mastering home voice overs and vocal recordings.
Get it right at the source... and the rest will follow.
If you want to learn more about room treatment and recording technique for recording voice overs, I shall cover more in future tutorials.
Perhaps you have already tried some of these materials as acoustic treatment. Let me know about your experiences, I’d love to hear from you.