Insulating a partition between rooms

[MisterBoy]

I am repurposing a log cabin building, it was originally built with this large opening in one of the internal walls:

In the new use, a large whiteboard has been added:

But obviously this is terrible for noise between the two rooms. I want a low-effort way to insulate the hole in the wall - it is 75mm thick timber so my thoughts are to use some sort of non-glass insulation roll (50/100mm), but then I came across low cost acoustic panels about 25mm thick for the same price per square m. I know neither will be perfect but I don't want to sound-proof, just provide some basic benefit.

 

[Wayners]

Acoustic panels stop echo noise. I don't think they do anything to stop sound.

You could use sound insulation foam in the wall maybe or rubber sound sheets

 

[MisterBoy]

Acoustic panels stop echo noise. I don't think they do anything to stop sound.

You could use sound insulation foam in the wall maybe or rubber sound sheets

yeah makes sense, I don't want to surface mount anything I just want to fill in the 'cavity' - there might well end up another white-board on the other side

 

[foxhole]

Roll of loft insulation would do it , (wool).

 

[Deluks]

Couple of layers of plasterboard in the hole. It's not great as it is.

 

[Tigercubrider]

Is there any insulation in the other internal walls?
I’d go for rockwool in the cavity, and plasterboard /timber over the faces.
Double up on the plasterboard if you can and use a mastic or similar to seal joins.

Sound goes around corners, so it the side room has a door that’s flimsy, you will still hear stuff.

That 25 mm “soundproofing” is mis sold. As said, it improves the acoustic performance like hanging curtains in a bathroom.
It won’t kill noise transmission.

 

[MisterBoy]

Is there any insulation in the other internal walls?
I’d go for rockwool in the cavity, and plasterboard /timber over the faces.
Double up on the plasterboard if you can and use a mastic or similar to seal joins.

Sound goes around corners, so it the side room has a door that’s flimsy, you will still hear stuff.

That 25 mm “soundproofing” is mis sold. As said, it improves the acoustic performance like hanging curtains in a bathroom.
It won’t kill noise transmission.

All the walls are solid 75mm timber. To clarify I don't want a sound-proofed room, I just want it to be as acoustically insulated as if there wasn't a massive hole in the wall. So it seems like regular insulation wool (non-glass) sandwiched as you and others have said is the obvious answer.

I did wonder about the door, there aren't big gaps anywhere but it is pretty thin. I'm open to replace it if that ends up being a problem but figured on doing the obvious thing first and then re-evaluating to see.

Thanks