How To Get Great Room Acoustics

 

Acoustics have three main properties which make any room good or bad for sound recording.

• The first is the resonance
• The second is the levels of reverberation and absorption of sound
• And the final is the diffusion and reflection properties.

When you understand these three basic qualities of sound, you will be able to identify the problems of acoustics in your room and then have the right kind of fix for it.

 

Resonance

When you hit a note and experience vibrations from the room, you have hit the resonance of the room. All rooms have resonances where the sound begins to bounce back and forth from one room to another. When you bring a sound to the resonant frequency, the sound takes much longer to fade out.

 

The resonance modes can be just between two walls or wall to wall. Some types of resonances are created with more than two walls as well. The wall to wall modes, however, always dominate the resonance in a room. In rooms with heavy resonances, recording of sounds is completely pointless. Unless the resonances are not fixed, the acoustics will continue to be spoilt.

 

The number of parallel spaces in a room can increase the resonances of the room. In a rectangular room, there are three different resonance modes. The first is the front wall to the back one, ceiling to the floor and left walls to the right ones. The wall to wall resonances, being the dominant ones, are the most important to be overcome. So before you move anywhere else, first try and remove the wall to wall resonances.

 

To eliminate resonances in your rooms, avoid recording in any room which has a lot of parallel walls. Rooms which are irregular in shape and which do not have any parallel walls, are ideal for being used as recording studios. In case you cannot avoid parallel walls in your recording studio, find out the resonant frequencies and try to fix them as best as possible. Still, if you find a room which does not have any parallel walls, it does not mean that the room will be perfect for your recording needs.

 

Reverberation and Absorption

When sound bounces of a surface, it is known as reverberation. A reverberation can be complete or partial. However, unlike direct echoes, these reverberations are heard only till the sound dies out. Based on the shape and the size of the room, the reverberations emanating can cause a different tone or pitch to the sound.

For creating a great recording environment, the reverberation needs to be controlled.

 

A room, in which there are no reverberations at all, is not that great for recording music. There needs to be some amount of reflection of sound for the music to remain pleasing. However, a room with a lot of reverberations can cause the sound to be blurry.

 

While artificial reverberations can always be added to the sounds post production, it is difficult to remove reverberations which are already present in the recorded sounds.

 

To ensure that your room has just the right amount of reverberations, first take into account the total space as well as the spatial volume of the room. Your recording room should not be less than 3,000 cubic feet in size. Any smaller than this, and the recording style will not be apt at all. In smaller rooms, the resonance will be too high to reduce through any methods.

 

Also, a smaller room will be too cramped to give you decent sounds. The studio should not be too large either. A studio which is larger than 30,000 cubic feet, will have too much of reverberations and you will have to get professional equipment to reduce reverberations in such a large room.

 

To check the reverberations, check the white noise by setting up a speaker and a microphone. Turn on the speaker as well as the microphone and then start recording immediately after switching them off. The aim is to record the decay of sound in the room. To make the reverberations right as you want them, try and make the room as dry as possible.

 

To prevent too much reflection of sound, a combination of reflective and absorptive materials should be used. Curtains, for instance, absorb mid range sounds. However, these do not have much impact on the lower range sounds. The thicker the material, the better is the absorption. Carpeting the room and using double felt drapes can help in ensuring that the sounds are reflected and absorbed in the right amount.

 

Bass traps and wall wedges are also required to absorb low frequency sounds. When you have a balance of these materials, according to the room space available, at different frequency ranges, you will hear different kinds of sounds. A little adjustment on the number of instruments used, and where these instruments are used, can help in making the room dry as well.

 

The sense of spatial placement also affects the overall reverberations of the sound in a room. The reverberation build up is usually different in different locations of the same room. Therefore, the instruments should be placed in a way that the room is able to catch the best of their sounds. Keeping the instruments as far away from each other as possible, gives those better sounds.

 

Reflections and Diffusion

Though reverberations are a kind of sound reflection, they are both different. Reverberation refers to a blend of many different reflections in a decaying pattern. On the other hand, reflection could be just a direct echo of the sound. Reverberations result in a blurry noise, whereas reflections give out a combing sound.

 

Reflection is usually caused when the instruments are placed too close to a hard and flat surface. The solution to this problem is rather simple. Just keep your instrument at least 1 foot away from where the mic is placed.

 

Also, try to keep the instruments away from any hard and flat surfaces. To get rid of flat surfaces, you can simply add things against them or scatter things in front of them so that the sounds do not bounce off them directly.