Sound proofing and acoustic treatment
Let us start with the basic difference between the two terms – sound proofing and acoustic treatment :
• We use acoustic treatment to get rid of or minimize reflections and frequency reinforcements, making the acoustic space good to record and mix.
• Sound proofing is the term used for preventing sound to enter or leave the room.
My recording bedroom
My bedroom doubles as the vocal recording room and mixing room. It is a small cubical room with cloth curtains on the windows, cardboard boxes, other general furniture and junk to scatter the sound and prevent the sound from bouncing around unobstructed.
There is no sound proofing to prevent external noise. Closing the windows and door is all that is done to that regard. Some of my recordings have birds and squirrels contributing with their music along with banging sounds made by some who wash their clothes nearby. For some reason i remember Led Zeppelin's story of recording the whole band with just one mic.
Small cubic rooms vs Bigger rooms or halls
Small cubic rooms are more trouble acoustically than a bigger hall with different measurements for length, width and height.
In a room with the same or similar dimensions for length, width and height, each dimension reinforces same or similar resonant frequencies (corresponding to the distance between walls), making it a big distortion in the way we hear the sound played in the space.
I still record in an almost cuboid room, with lot of junk in it. But i work most of the time with AKG K271 headphones, using the Rubicon R8a speakers to listen to the bass frequencies and stereo placement.
Cardioid pattern mics and close micing
When the vocalist holds a cardioid patterndirectional mic like SM58, within one inch from the mouth, the surrounding sounds picked along with the vocal recording is negligible.
The room sound, the reflections are also picked up to a minimum when we close mic SM58.
A cardioid pattern mic picks up the sounds on its axis much more than from any other direction. It has a null point behind the mic.
Mixing with reference – the mind game
When mixing in a room which has not been treated acoustically, we have to be careful when making mixing decisions – working with the equalizer, the reverb.
Well produced commercial CDs are made to sound the best in different listening situations. Listen to how they sound in your room. Then make your songs sound similar to how the commercial productions sound in your room.
Withhold making absolute judgments. Try to imitate the different parts of the frequency spectrum of a commercial production when you work with the frequencies and reverbs in your mix.
An internal equalizer
This is almost like we have an internal equalizer. We use the reference songs, tweak our internal equalizer, to see how the frequencies behave. Then we use this understanding gained from how the internal equalizer has to be different from a flat response, while mixing our songs in the given space. Resist the urge to just tweak, slow down and see the details, remember it is not as it sounds to be, tweak according to the discernment we gained from the reference songs.
Your reference song playlist
Have a set of reference songs – well produced commercial music. Get familiar with how they sound in your studio or room through your system.
The room may have boosts in specific frequencies. Listen to reference songs and know how the frequencies behave in your environment. Instead of boosting or reducing frequencies from what we hear, consider it with reference to how the commercial CDs sound and make your songs closest to the way they sound in your room.
Even well built studios will have different ways of reproducing sounds.The speakers, their positioning, the acoustic environment of the studio. Reference mixes whose sound we are familiar with will help us understand the new space by listening to how the reference sounds in the new space. Listen to how they sound in the new place if you are mixing in a new place. This lets you understand the acoustics of the current listening environment, each time you are in a new acoustic situation.
See Ethan Winer’s very good resource on Do it Yourself acoustic treatment. Ethan is an authority, his acoustic treatment products are used all over the world.
Curtains, thermocol etc help reduce boosts in the high and mid frequencies. But if the bass frequencies have to be controlled, we need to use specific material like rigid fiberglass.
In my experience acoustic treatment materials are usually available with Air Conditioner installing contractors because they need it for insulating loud noise making ACs from rest of the building. They will have the skilled labour too. Rock wool and similar material can be extremely itchy – so have gloves, helmets.
If you have taken some basic steps to reduce reflections and avoid boomy rooms, don’t bother too much about the bass frequencies and other room sound (reflections) while recording. This is especially true if you are using close micing and dynamic directional mics like SM58. But while mixing remember not to make decisions solely based on how we hear the bass frequencies.
A room with enough furniture for absorption and diffusion is a good place to record. A cozy environment is a good addition to improve the performance comfort.
I record on my laptop with a configuration of 1 GB RAM, 1.73 GHz Dual Core processor.
Using this laptop, i have made songs that have vocal groups, string arrangement, 3 pads, drums and percussion tracks, bass track, flute, piano and more embellishments. 60 + tracks in some detail songs. Most of the audio tracks with compressor, two reverb plugins used through the send channel of the individual audio track.
Many basic laptops these days have a configuration at least as good or better. For most of our purposes we won't notice any processor or RAM shortage. Desktops come even more powerful and are cheaper than laptops – in which case there is lower chance of you getting into trouble with the computer resources being insufficient for your project.
Once I read a suggestion to not sit in the middle of the room while monitoring because especially the bass frequencies get exaggerated. In the beginning I used to try take care of small details like that, but slowly I started leaving such specifics.
More the junk in your recording room, more the sound is scattered, better the acoustics. A room with less objects in it lets the sound to bounce back from flat walls. Have curtains on the windows.
If possible, avoid small square rooms with hard walls, as these can sound very boxy. In fact large halls are easier to treat acoustically than small rooms. A cubic room – length width height all the same is the worst because each of the dimensions reinforces the same frequencies to exaggerate.
Keep the mic away from walls and corners, Hang up absorbent material against the walls if the room sounds too 'live'.