There is a huge difference between sound treatment and soundproofing. It's important to understand the two different processes and how they impact an acoustic environment.
Soundproofing is all about sound isolation and has nothing to do with treating the acoustics in a room. The objective of soundproofing techniques is to make the room "quieter". Sound treatment, on the other hand, is a way to make better-sounding recordings inside a room by controlling sound reflections. The goal of sound treatment is to make the room "sound better".
Assessing Your Room's Acoustics
It's important to remember that all rooms have distinct acoustical characteristics. Because of this, we must analyze the acoustic properties of the space before applying appropriate sound treatment. Let's take a look at some vital concepts, situations, and terms.
Reflective Surfaces
Start by identifying the problem areas in your room. Reflective surfaces (large windows, mirrors, hardwood floor/laminate, and tv screens) have a knack for bouncing off sound reflections at fast intervals. These echoes and reflections lead to a perceived increase in clarity and volume because the sound waves overlap after hitting a hard flat surface.
Example: Do you remember what a bathroom or garage sounds like when it is completely empty? The echoes and reverberation are a result of reflective surfaces bouncing the sound waves all around the room.
Large and Small Room Acoustics
Large rooms are prone to acoustical issues like standing waves, nodes, and large amounts of reflections. On the other hand, small rooms can have problems with lower frequencies because the sound wave doesn't have space to develop.
Both large rooms and small rooms can lead to mixes that don't translate well.
Reverberation
Reverberation is a phenomenon where sound continues after the noise source has stopped. This audible persistence comes from the sound waves reflecting off of surfaces and objects (people, furniture, walls/ceiling/floor) in the room.
The scattered sound reflections build upon each object they hit and the soundwave's energy will gently fade with each reflection as it is absorbed by the surfaces in the room.
Simply stated, the resonating persistence of sound is called reverberation.
Example: When piano keys are released after striking a chord, the sound waves continue to travel until they run out of energy and eventually stop.
Frequency
Frequency refers to sound vibration's speed and it determines the sound's pitch.
The number of sound wave cycles occurring in a single second determines the Hertz (Hz for short).
Humans with undamaged hearing can perceive sounds between the frequencies of 20 Hz and 20,000 Hz.
When analyzing the acoustic issues that need to be resolved in your studio room, start by identifying what frequency of reflections your room is emphasizing. This will help you properly treat the sound issue.
How to Acoustically Treat a Room - Sound Absorption
The first acoustic treatment technique we'll discuss is sound absorption.
This is the most common method of sound treatment that people use. It is probably overused in most rooms. In some studios, this will be the only sound treatment you will see - and frequently, far too much of it is being used.
This popular method of acoustic treatment includes acoustic foam sheets, absorption panels, bass traps, sound blankets, and insulation. In many studios, this is the primary sound treatment that you will see throughout the room.
However, you don't need to go overboard with sound absorption and cover every square inch of your wall. Too much absorption will give your room a very "dead" sound and can negatively affect the mix of your audio.
Here are some important characteristics of sound absorption:
- Does not block noise
- Improves sound quality
- Absorbs sound waves and certain frequencies
- Reduces echoes and reverberation
Let's discuss how the absorption technique works and when to use it.
When to Use Sound Absorption
Absorption is needed whenever there is a lot of reverberation taking place.
Reverberation sounds in your room will appear as echoes and bothersome ringing noises that come from mid and high-frequency noises. These reverberating sounds are called early reflections and late reflections. Early reflections are the sounds that arrive to our ears first from the direct source and late reflections spend more time bouncing around the room before we hear them. However, these numerous reflections happen so quickly at different intervals that our brain perceives it as one sound with a lot of added reverb.
When these reflections go untreated, they can exhaust the listener and overwhelm the brain's ability to make sense of the audio's integrity in order to make a proper mix.
How to Treat Low Frequencies
Low-frequency energy is more difficult to control because the sound waves are much longer than higher frequencies. Therefore, conventional sound treatment panels aren't as effective.
Thick and dense material needs to be used to tackle low frequencies. Thankfully, bass traps exist. You can combat low-frequency noise issues by strategically placing bass traps in the corners of the room.
Treating the Entire Room
For the best results, try to cover at least 1/3 of your space with sound absorption material.
- Every room is different based on objectives
- Some studios have a "live" room with minimal sound absorption
- VO and vocal recordings typically want a very "dead" environment
To make sure that sound is absorbed from as many directions as it can be, spread out the acoustic treatment as much as possible. Lastly, the trick is to do things a little at a time.
How to Acoustically Treat a Room - Diffusion
Areas of bare walls will create reflection. This can give you a horrible slapback style of delay that is far from desirable in your studio. Remember, flat surfaces such as computer screens, desks, walls, and windows create these unwanted reflections.
Thankfully, there is an answer for unwanted reflections and it is called diffusion. This is similar to reflection, but instead of all the sound being reflected at once, it is "diffused" and returned to your ears at many different intervals.
Diffuser panels are made up of many small segments. These may appear random at first but are designed using exact mathematics to reflect sound in a desirable manner.
Believe it or not, a little reflection of sound in our workspace is a good thing. Diffusion disperses sound and helps our ears hear the mix come back from different parts of the room. This makes the audio sound more natural to our hearing.
Decoupling Monitors
Believe it or not, studio monitors can cause acoustic issues if they are not positioned correctly in your studio. Fix this by decoupling your monitors to avoid unwanted sound vibrations that occur when monitors are placed directly on a desk or table.
The reflected sound waves that are hitting the desk can interfere with the sound waves that are coming directly into your ears. This results in not hearing an accurate representation of what is coming out of the monitor mix. The use of monitor stands and isolation pads will reduce vibration transfer and low-end build-up in the room.
Listening Position
As it’s almost impossible to entirely kill sound reflections, you can consider positioning yourself and the speakers in a position that will be most beneficial for your work. Let's take a look at the ideal listening position:
- Place your speakers at the same height level as your ears.
- Form an equilateral triangle between yourself and the two speakers.
- If you can, set this triangle up 2/5ths of the length of the room away from the wall (this will help minimize the reflections and the dreaded bass null - the spot in the middle of the room where reflections can cause a drop off in the bass end of your speakers' response).
Although these concepts are universal for any audio recording task, they are especially applicable when mixing!
How to Soundproof Your Room
Two things happen when a room is perfectly soundproof. Outside noises stay outside and don't disturb your recordings, while inside noises stay inside and don't disturb your neighbors.
Careful planning needs to be done before a soundproofing method can be applied to a room.
There are 4 tactics for soundproofing a room:
- Adding Mass
- Damping
- Decoupling
- Sealing Air Gaps
Structure-borne vs. Airborne Sound Issues
The first step to fixing your noise issue is to understand it. If your AC unit and plumbing system are the culprits of the noise, then you have a structure-borne sound problem. If the neighbor's barking dog or traffic sounds find their way into your recordings, then you have an airborne sound issue.
1. Adding Mass/Density
This soundproofing method implies that you need to add more mass to your walls and make them heavy enough not to vibrate.
You can minimize how much sound a wall transmits by simply adding a second, third, or fourth layer of drywall to it. Other materials that work well to add mass/density are medium-density fibreboard (MDF), plywood, mass-loaded vinyl (MLV), bricks, cement board, and oriented strand board (OSB).
Adding mass will not create an impenetrable sound barrier, but it makes a wall heavier and more difficult to move with sound and vibrations. To make adding mass more effective, you need to combine it with damping or decoupling (or even both).
2. Damping
Damping is a technique for soundproofing a room where you add material to the surface of the walls to help remove vibrations. The damping material helps reduce unwanted vibration or shock by soaking up the vibrational energy.
Material to position in between a layer of mass for damping:
- Green Glue
- PVC
- Foam Composites
Damping is a relatively new soundproofing technique that removes vibration energy by eliminating the dynamic stresses associated with vibration. By itself, damping is not a very effective technique. However, it is useful when combined with other soundproofing measures.
3. Decoupling
If you want to keep sound from traveling outside the walls of your room, you will need to decouple the solid layers to help prevent vibration from traveling to the outside. Decoupling involves separating the framings in your walls and ceilings to create a room within a room.
A common decoupling approach is called "double framing". This method creates a gap between the inner layers of drywall and the outer layers that combat soundwaves from passing outside of the room. It's popular to fill the double-framed air gap with insulation to reinforce the soundproofing method.
Fully decoupling the framing (walls and ceiling) from the existing structure is a powerful way to isolate sound. Additionally, decoupling combined with insulation works even better.
However, keep in mind that decoupling usually involves permanent construction in your room.
4. Sealing Air Gaps
When soundproofing a room, don't forget to seal seams and gaps. Any air gap or seam will allow sound to spill into or out of a room. Pay special attention to doors and windows. Acoustical sound caulk and weather stripping work great at sealing gaps to help you create a soundproof room.
Remember, if any light or air can pass through the gaps in your room, so can sound waves.
To Conclude
We hope this article helped you learn more about the difference between sound treatment and soundproofing. If you have any questions or if you would like to learn more about how WhisperRoom can help you achieve a desirable room for recording, producing, and mixing audio please email info@whisperroom.com.
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