[Home Studio DIY 03 : Room Acoustics] A frequency that only rings in my room

My room after moving studios, roughly organized considering room acoustics.

It's an ordinary two-room house.

 

It's still a decent room for making music, even if acoustically, it's not ideal.

 

First, I measured the size of my room. (width, length and height)

size of my room for music studio

 

 

After measuring the size, I used the following site to estimate the frequency bands

that could be problematic:

 

https://amcoustics.com/tools/amroc?l=9&w=9.7&h=7.2&ft=true&re=EBU%20listening%20room

amroc - THE Room Mode Calculator

 

 

 

Before using this site, let's first go over what 'resonance' and 'room mode' are.

 

Room mode; literally translated, it means 'the maximum frequency of a room', right?

 

You might wonder what that means. Then let's retrace the experiences we already know.

 

Have you ever blown air into an empty bottle with your mouth and played a bottle flute?

You'll notice that the pitch of the sound changes depending on the volume of the bottle.

 

The principle behind how this sound is produced is 'resonance'.

 

Now, let's think of the room we work in as a giant empty bottle,

and the speaker as the lips that blow air into it.

 

Wouldn't a sound of a specific pitch resonate like a bottle flute?

 

Simply put, this is called room mode.

 

In other words, the amroc site calculates what pitches (=room modes)

will resonate in the giant empty bottle that is the room.

 

(Of course, calculations based on wall thickness and material,

how uneven the four sides are, and the location and

thickness of windows are too difficult, so please use it only as a rough estimate.)

The room mode of my room

 

Anyway, if you just hit the calculator, this is what comes up.

 

Do you see the protruding bars at the very top?

 

Those are the sounds (=frequencies) of problematic pitches in your room.

 

There are a lot, right?

 

In my case, it's roughly

 

47Hz

66Hz

76Hz

89Hz . . .

 

This means that sounds resonate at these frequencies.

 

The various terms below- ex) Bolt Area / RT60 / Schroeder frequency / Critical distance, etc.

will take a long time to explain in detail,

 

so I'll explain them later.

 

Anyway, with a square structure, low ceiling height, and a smaller room size than expected,

contrary to expectations, there are a lot of problems.

 

So I made the following plans:

1. Low frequencies are difficult to control, so let's put in a lot of mineral wool. More than you can imagine.

= Buy about 15 packs of 48k 5cm100cm10 mineral wool.

---

1. Since the ceiling is low, acoustic clouds are a must!
   
   
2. Spending on mineral wool is bigger than expected.
   I'll cut the wood with a saw and make the frame myself.
   
   
3. Let's make the floor as flat as possible. To make variable control easier.

---

 

If you think the scale is getting bigger and bigger... you're right.

It turned out like this.

 

The beginning of hell. Removing the linoleum, repairing cracks, and applying self-leveling mortar to level the floor.

 

Grinding time-lapse