Live Streaming: Acoustic Treatment

Concentric ripples of water

The term “acoustic treatment” conjures dread thoughts of great expense and bewildering complexity; and in the world of professional, high-end audio, this is all too often the case.  In truth though, at least in its most basic sense, everyone of us has already “acoustically treated” countless rooms.

When moving into a new home, we quickly begin to add rugs, soft furnishings, and curtains, etc.  We do this because it “feels” nicer, more homely to us.  We do this because an empty room feels noisy, cavernous, and cold.  We do this to make noisy quiet (soundproofing), to make cavernous cosy (absorption), to make cold warm (diffusion).

For the purposes of the article, let’s simplify things and assume that Acoustic Treatment consists of three basic principles:  Soundproofing, Absorption, and Diffusion. 

1. Soundproofing

Typically noise “leaks” into a room via the door(s) and window(s).  Targeting these specific areas can make big differences.  The use of draft excluders at the base of doors and drawing the curtains (although at the expense of natural light) will help to reduce noise pollution from outside.  Replacing conventional insulation with silicone insulation* around windows (and doors) will result in a considerable reduction. 

*Silicone Insulation is relatively expensive when compared to conventional options.  It is, however, surprisingly effective.  For example, my dog now stays calm and happy when they’re are fireworks.  Priceless for any dog owner.

2. Absorption

The behaviour of soundwaves is complex and well beyond the scope of this article.   

For our purposes, let’s imagine a perfectly flat plane of water stretching out in infinite directions; this is silence.  If we drop a stone into the water, ripples spread outwards across the plane, in a perfect pattern of expanding circles; this is sound.

Now imagine we enclose the plane of water within four rigid walls.  When we drop a stone into the water, the ripples reach the walls and rebound causing disturbances; our pattern is no longer perfect, but messy and unclear; this is sound in a room without acoustic treatment. 

Now let’s replace those rigid walls with surfaces that flex and give.  When we drop a stone into the water, the walls flex and shift to match the movement of the ripples.  The ripples still rebound, but the disturbances caused are less.  Although not perfect, our pattern is recognisable and defined.  This is how absorption works.

When thinking about aborption in the room you’re using for live streaming, it is best to think about key/problem areas.

i) Corners
Sound is inclined to “pool” in corners. This is particularly true of bass frequencies (and why you will often see bass traps in the corners of recording studios). It is also why we’re inclined to full corners with plants or furniture, etc. We are instinctively acoustically treating our living spaces.

ii) Floors and Ceilings 
Floors and ceilings represent large flat surfaces likely to reflect and cause the sound in the room to become muddy or unclear.  Ceilings are difficult to deal with; without professional acoustic panels, and are best left alone.  Floors, on the other hand, are much easier to deal with; a simple rug will do much to improve the clarity of sound in your live streams. 

iii) Within the Room
If your home is sparsely decorated, adding cushions, throws, and table cloths, etc will help to “soften” hard surfaces and add to the amount of absorption in the room.

However if your room is already richly decorated, you may improve results by emptying the room out a little more. Sound needs space to resonate properly. A room packed with absorption will result in a “dead sound”*.

*much like a small vocal booth is good for voiceover, but poorly suited to vocal recording.

iv) Windows and Doors
Windows and doors tend to be made of smooth, hard surfaces; not ideal for sound.  Curtains or, if you wish to use natural light, net curtains* can help to absorb sound.  And simply hanging coats, etc off the back of doors will introduce some absorption.

*though net curtains will, in truth, offer more diffusion than absorption.

3. Diffusion

Let’s return to our plane of water, enclosed by four flexible surfaces.  Instead of having four flat surfaces, let’s make the surfaces uneven and random.

When we drop a stone into the water, not only are the ripples absorbed to an extent, the rebounding ripples are sent off in all different directions by uneven and random surfaces; this has the effect of reducing the intensity of the rebounds (or “diluting” them), thus making our original ripple pattern even easier to recognise and more defined.  This is diffusion.   

Diffusion can be achieved by anything that introduces uneven surfaces into an otherwise flat surface.

i) Bookcases
Bookcases filled with books are extremely good at creating an uneven surface of diffusion.

ii) Pictures
Pictures hanging on walls will also serve to break up an otherwise consistently flat surface.

iii) Plants
Plants, given their organic mess of shapes, can provide a natural form of diffusion.  

iv) Decorations/General Clutter
In fact anything that adds variation to the surfaces will diffuse the sound to some extent.

FINAL THOUGHTS
It is worth noting that there is a good deal of overlap between absorption and diffusion (and, in fact, soundproofing too).  For example, hanging coats on the back of a door will offer absorption and some diffusion.  Net curtains will offer a little absorption and more diffusion.  

The degree to which you need to treat the sound in your room will depend on the size of the room, how it is decorated to start with, and, of course, how you choose to present your style of music and how you want your audience to experience your music.  

The physical space in which a sound is recorded goes a long way to determining the emotional feel of that sound.  Imagine the sound of someone singing a ballad in a small living room or similar.  Now imagine that same ballad sung in a cathedral.  The emotional experience is quite different.         

Tobi

Tobi works as a Mastering Engineer (via Tobisonic Mastering), mastering a wide range of genre. Tobi also remixes and has recently released his debut solo production, All These Things under the handle Tobisonics. Find him on Twitter @masteredbytobi Read More.

2 Comments

  1. All top advice Tobi!
    Thanks for taking time out to post all these great tips.

  2. Thanks! Appreciate the kind words and taking time to comment! Stay safe & stay healthy!

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