Bass traps

[bigjimmyc]

Hey all.
Looking for some advice on acoustic damping for my shed.

I have a very nice log cabin in my garden which has been used as a rehearsal room, ofice, movie room, general man cave etc.

By and large it's well insulated for sound and heat, but we have a motorway not 20 feet away and the main noise which comes into the room is seriously low frequency, i.e. Ground transferred vehicle noise.

I'm wondering if an investment in bass traps would pay off? If so, what to buy and where to install for maximum effect??

Any and all advice gratefully received.

[KingPrawn]

Hello. They are usually placed where two reflective surfaces meet. So in corners and where ceiling meets walls etc. They do deaden the room quite considerably. I made my own, which allowed me to make the bespoke and to the sizes I needed. My understanding is that they have more of an impact on sound generated inside the room. I'm not sure how they effect the frequencies your trying to keep out?

This is the ones I made. Really cheap and far more decorative as you can choose fabric to suit.

https://www.readyacoustics.com/DIY-BASS-TRAPS-MADE-EASY.pdf

[BigRedX]

Bass traps have zero impact on noise coming in from outside. They are designed to solve acoustic problems with standing waves within the room itself. To prevent noise from outside, especially low frequency, you need to acoustically decouple the inside of the structure from its surroundings. That normally means a floating floor and a room within a room.

[Damonjames]

[quote name='BigRedX' timestamp='1502987478' post='3354898']
Bass traps have zero impact on noise coming in from outside. They are designed to solve acoustic problems with standing waves within the room itself. To prevent noise from outside, especially low frequency, you need to acoustically decouple the inside of the structure from its surroundings. That normally means a floating floor and a room within a room.
[/quote]

This!!!! In the real world though, this may not be achievable in a log cabin style man cave.

The only way to stop the sound from outside is by increasing the mass of the walls.

Try this site for some more info

http://www.acoustic-supplies.com/wall-soundproofing/

I'm about to set up my practice room over the next few weeks, so I will set up a thread somewhere for info.

Good luck!!

[bigjimmyc]

Great input so far, cheers. In my head the noise comes from the floor. Is that correct?

Either way, noise in the room can be absorbed (not reflected) at the walls and ceiling, or is that a fallacy?

[BigRedX]

[quote name='bigjimmyc' timestamp='1502991310' post='3354939']
Great input so far, cheers. In my head the noise comes from the floor. Is that correct?

Either way, noise in the room can be absorbed (not reflected) at the walls and ceiling, or is that a fallacy?
[/quote]

You have got two different things here. One is isolating the the room so that outside noise doesn't get in (and also so noise generated inside doesn't get out). That is soundproofing. The other is treating the inside of the room for directional noise generated within the room itself. This is acoustic treatment.

Outside noise comes from everywhere, and will get into your building through the least insulated part. Generally low frequency rumble is transmitted through materials so will appear to be coming through the floor. However simply uncoupling the floor inside will not be enough if you don't also uncouple the walls and ceiling. Hence the room within a room.

Bass traps are designed to absorb standing waves generated by the speakers inside the room so that they don't reflect off the internal surfaces of the room. Generally you find them situated on the wall the speakers point at plus corners of the wall and even the ceiling. If you don't absorb these waves they reflect back off the walls and will create peaks and troughs at different frequencies at different point in the room as the reflected sound waves add and subtract from the direct waves. This means that you get a different frequency balance at different points in the room.