You may be under the impression that the more acoustic treatment, the better. Some recording studios spend thousands to have every surface covered with acoustic treatment. But is heavily investing in acoustic treatment such as foam, bass traps, and other methods the best way to get your podcasting studio sounding its best? Read on to find out if there really is such a thing as too much acoustic treatment.
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What is Acoustic Treatment?
Reverberation is essentially the amount of reflection created by a space. It is the indirect sound created by a sound source. A room is likely reverberant when it is a lot easier for sound to be kept inside the room and reflected within the room. This is why a room that has one or more of the following features is likely to be more reverberant:
- Large dimensions
- Reflective boundary surfaces
- Dense boundaries
- Parallel boundaries
And a room is likely less reverberant when sound can escape the room easily and is not reflected well within the room. This is why a room that has one or more of the following features is likely to be less reverberant:
- Small dimensions
- Absorptive boundary surfaces
- Porous boundaries
- No parallel boundaries
A room can be described as having a reverberation time (RT) which can be plotted to show how different RT at different frequencies within the room.
Acoustic treatment is often used to change the RT time to a recommended level for the given situation or room type – this varies for different spaces and will be explored in more detail within the Acoustic Treatment for Podcasters section.
Acoustic Treatment Types
There are multiple ways of achieving the desired acoustics for a space.
- Absorption: Probably the most common form of acoustic treatment, absorption can be achieved through acoustic foam, which is typically placed on the walls within a space. It is typically most effective in reducing high-frequency content.
- Bass Traps: These can be used to reduce low-frequency content. Low-frequency content will likely cause the most acoustic problems within a space, because they have more energy than higher frequencies, and so bass traps are extremely useful. They are typically designed to be placed in the corner of rooms to reduce the high-energy that builds up where two boundaries are extremely close.
- Reflection: This can alter the RT by changing the points in a room in which reflection occurs. This can be done using acoustic paneling, which are large panels that act as walls within the studio. Doing this can be effective in reducing the effects of standing waves, this is where sound waves reinforce each other and are typically caused by parallel walls.
- Diffusion: Diffusion panels essentially scatter any sound waves that hit them. Like reflection, diffusion can prevent standing waves. They can often keep a space reverberant overall while still removing distinct or problematic reflections.
Are You Using Too Much Acoustic Treatment?
As previously mentioned, all this equipment can be expensive, so is there a point where it doesn’t make sense and you start to waste money when purchasing acoustic treatment?
Often it is recommended to aim for an RT time that is even over the frequency spectrum. In the image shown previously, the room has an RT that is too high at lower frequencies. Someone with less knowledge in acoustics who wants to set up a podcast studio in that room might hear the reverberation and think that adding the absorptive paneling that we so often see in studios will reduce the RT, fixing the acoustic issues.
In reality, it is likely this will only attenuate higher-frequencies making the room sound more ‘dead’ at high frequencies while making the lower-frequencies even more prominent.
Even if you are successful in reducing the RT evenly across the frequency spectrum, using too much can lead to a room not sounding ‘lively’ enough and sounding unnatural. This will mean you’ll likely be spending time adding artificial reverberation to sounds that you record in your studio.
Some spaces may not even require acoustic treatment if a space has low and even reverberation anyway. I’ve had people tell me of studios that have very little acoustic treatment when in reality these places implement acoustic treatment hidden in the architecture of a place to achieve an ideal RT.
For example, curtains and furniture are intentionally implemented, and people often forget how absorptive they can be. Also, surfaces can be made convex or rounded to prevent the effect of parallel walls, plus, walls are specifically designed with multiple layers to reduce reflections. Adding lots of acoustic foam to this studio is likely to disrupt spaces designed like this.
Of course, this is more applicable to professional studios. If you’re wondering how much acoustic treatment is too much within your home studio, read the How to Test if You’re Using too Much Acoustic Treatment section to learn how you can find out the RT of a space yourself.
Acoustic Treatment for Podcasters
So why is acoustic treatment so important for podcasters specifically? Well, the unnatural sound that can be experienced in a ‘dead’ room can be overcome simply by applying reverberation during your edit. However, arguably, whoever you’re recording probably won’t like talking in a room that is so ‘dead’, it makes the environment feel uncomfortable and difficult to relax in; psychologically this might alter the mood of whoever is speaking, as they aren’t able to be their normal self.
This will result in your guest potentially not being as lively as they normally are, which could reduce how interesting the podcast is to any listeners of your podcast. It could also encourage a guest-speaker not to return as a guest to your podcast.
Standard BB93 is a standard from the UK that states the optimum RT for a control room for recording is no higher than 0.5 seconds. I’d recommend this value to be also used for podcasters. Aim to keep an even RT over the frequency spectrum that is close to but no higher than this value. To read it yourself, the standard is available for free at https://www.gov.uk/government/publications/bb93-acoustic-design-of-schools-performance-standards
How to Test if You’re Using too Much Acoustic Treatment
If you’re planning to use acoustic treatment for a space and don’t have much time it might be worth checking out a website such as acoustimac.com (https://www.acoustimac.com/room-calculator), which will tell you how much acoustic paneling you’ll need. This can be inaccurate as there is little justification for the output given by these websites and they do not consider anything other than the dimensions of the space, although it can also be an indication of if you’re using too much acoustic foam already.
A more sophisticated method is to record a balloon burst using your recording setup. This recording can be opened using Room EQ Wizard, which is freely available software. Room EQ Wizard can tell you the RT and how even the reverberation is over the frequency spectrum. This will be influenced by the frequency response of your microphone, however, which can be read about here (https://www.theseasonedpodcaster.com/how-to-guides/how-to-test-microphone-frequency-response/) and balloon bursts aren’t known to be the most accurate at producing a sound that is even over the frequency spectrum.
Doing this isn’t always necessary, however. If you’re recording speech, it is likely that there is not too much difference for RT over the speech portion of the frequency spectrum, so simply testing that your speech is intelligible and natural-sounding can be a good enough indication of if you’re using roughly the right amount of acoustic treatment.