How Soundproof Is My Studio?

acoustics home recording studio low frequencies noise criterion curve soundproof soundproof door soundproof studio soundproofing spl meter Mar 27, 2023

In 2020 I built a soundproof studio in my backyard. I had no prior experience building studios and I primarily used Rod Gervai's book, Home Recording Studio: Build It Like The Pros and the advice from The Soundproofing Company to design and build my studio. In this article I want to show you how soundproof my studio actually is, so you know what level of soundproofing you can achieve with these methods.

1) Taking SPL Measurements

Before you build your studio you can take SPL measurements as many times as possible each day for 7 days to see what the highest reading you get is. This will be the SPL reading you need to soundproof against.

In my studio I recorded an SPL of around 26dB. I took this measurement at 9:17am on a Monday morning. I then went outside and measure the ambient SPL of my neighborhood right outside the front door of my recording studio. The peak readings I got while outside was 57.6dB. So my transmission loss, or TL for short, was 31.6dB.

Now it is important to note that not all frequencies have the same TL. So low bass frequencies will pass through my soundproof structure more easily than higher frequencies. Our goal with soundproofing is to try and reduce the sound outside as much as possible, while also reducing the loud sounds in our studio from coming out into the neighborhood.

The best way to do SPL measurements for your studio is to take as many as possible at different times of the day. For example if you hear a siren passing by, pull out your SPL meter and record the level. This will help you get an idea for peak SPL levels in your studio.

2) What About Loud Music In My Studio?

So in this test I did while playing my monitors, I reached an SPL of 87.6. When I closed my door while the speakers were still blasting the SPL outside dropped to 48dB. That means there was a TL of 39.6db. We also know that 48db was the ambient SPL of my backyard, so essentially my studio blocked out all the sound of the speakers at a very high listening level. I would never mix or listen back as loud as I was playing them.

For drums there would certainly be a higher SPL in the studio and thus maybe a higher SPL right outside. I will have to do that experiment the next time I have drums in the studio.

3) Okay, so what do I hear in my studio?

After working in my studio for 2 and a half years I can say that a take has never been ruined due to outside sound. That is not something I can say for my home studios previously. I can also say that when we play with drums or a full band in the studio the neighbors have never complained. I do not use the studio at all hours of the night, but I am confident it would not be a problem.

Now I do hear some noises. Super powerful sub bass from cars in the apartment complex behind my house will enter the studio, but only in very low frequencies like 40hz and below. That is annoying, but you can EQ that off in most recordings. It is also fairly rare.

I can hear thunder, but again it is only the low frequencies and it really doesn't come through much. I cannot hear rain at all.

If a helicopter is flying really low I might hear some of its lower frequency energy, but it is not super loud.

Lastly, if they are mowing the lawn, it really doesn't matter unless they drive the lawnmower right by my door or directly up against the back wall.

4) How My Studio Could Improve Soundproofing

My door...oh my door. What a headache it has been. It has cost me so much time and money. If I could do it all over again I would have designed a communicating door system with Zero Industry seals going around each door. I also would have used the JH Brandt method of door construction not Gervais's. I would have used Corning 703 wrapped in fabric between the doors to increase transmission loss.

One day I plan on adding a second door and better seals, but my budget currently does not allow for it and honestly it doesn't affect my work. It is more of a nerd and ego thing to make my door as soundproof as possible.

This said, I am confident that I would hear even less if my door had been built better the first time through.

I hope you have found this article insightful and helpful in understanding how soundproof a studio can be and how soundproof my studio is. Remember, you cannot eliminate all sound, but you can reduce it to an acceptable level for professional level recording.

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