Considering and planning a cabin for vocal practice

[HeavenWraith]

Greetings,

I live in an apartment block and have a bedroom studio, where among other things I practice and record vocals. Everything is peachy, with one caveat - although I'm lucky(?) to live in a chilly weather country that has great insulation between apartments, disturbing the neighbors is still somewhat of an issue. I can practice in afternoon/early evening without anyone minding, but I'd really like to extend that time window. For that purpose I'm considering a cabin/booth.

I did some quick noise measurements to get an idea of how much soundproofing I need:
* My voice peaks at around 100dB, I don't think I ever beat 105dB (measured at about 5cm in front of my mouth).
* The fundamental of my lowest note is around 100Hz, so there's hardly any meaningful energy below that point.
* I can hear absolutely no sound coming from the neighbors that are on the same floor as me. The side walls seem to be really well isolated. Only neighbors above and below are an issue.
* Occasionally, I hear a child screaming at night from the neighbors above me. I assume the actual sound level of that is around 90-95dB, what can be heard in my flat measured to around 50-55dB.

With that info in mind, I figure an attenuation of 15-20dB would be plenty to take the edge off my voice, and the insulation between the apartments would do the rest. I considered some pre-made products like VicBooth Ultra and they seem plenty to achieve my goal, albeit with really inflated prices.
I'm still in the process of figuring out the exact available space I have for this project, but for now let's assume I have these dimensions to work with: 1100 x 1500 x 2400 (mm). Naturally, I would want the walls to be thin and that's the tricky part where I'm not sure whether a double-leaf with a small cavity or a single heavier leaf would be better. VicBooth advertises 30dB attenuation with the thinnest wall being ~30mm, but from what theory I have read so far it seems really unlikely in a DIY scenario. And from what I understand a two-leaf system is only effective if the door is doubled too (one opening to the outside, one to the inside), which might be really tricky in a booth this small.

So my main conundrum is whether this project is even worth attempting with that little space?
If yes, is a two-leaf system something I should do or can I get by with just a single drywall/plywood/etc layer?
If a two-leaf system is to be considered, from what I read I figured it would only be useful if I bring the resonant frequency below 100Hz. Is that correct?

I'm still working my way through the articles/threads on ventilation, wiring and other mandatory components that I will have to consider and plan out.
I don't have a hard limit on the budget, but for planning purposes let's assume there is $3000 available.

Thanks a lot and have a nice day!

[gullfo]

welcome.

likely the baby sounds (and your sounds) are/would be transmitted via windows and perhaps some structural transfer.

so, maybe some window plugs and for your amps/speakers some isolation platforms. depending on the floor construction (might be reinforced concrete?) it might be all you need. do some testing, and if you're friendly with the neighbors, ask if you can do some testing to determine what levels of isolation you really need after blocking the windows.

[HeavenWraith]

Thanks a lot for the information.

The thought of trying to fix the sound leaks in the whole room did cross my mind a few times before. With some creative craftsmanship plugging the window should be possible, but there's also stuff like a vent, a leaky door leading to a less soundproof room, and whatever other structural issues might lie there. I'm afraid that this process has the potential to be quite frustrating, and for a building/engineering layman like me that would involve employing acoustics experts to analyze (who may or may not exist in my city). I'd like this to be plan B, plan A being a vocal booth inside my room.
I'm definitely planning to do some level testing at the neighbors' place, but this will have to be sometime in the future - my country is still under heavy quarantine.

While digging around for information, I played around with the MSM Transmission Loss Calculator and figured that a single-layer cabin would probably be good enough for my needs (pending level testing at the neighbor's place). I think I will try to sketchup a design for a cabin that would fit in my room, and then come back with more precise questions.

[gullfo]

best bet - skip too much analysis on the leaks, shared vents, windows etc and just plug the leaks, build window plugs (they're pretty easy to build although i recommend building them as "hinged shutters" so you don't have to try to lift them up and down), and for your "live" specific rooms, you may need/want to build some silencers for the vents to reduce/eliminate that source. once that's done, then you can start to consider the structural noise because before you fix the main and obvious sources, you won't get clear picture of the structural transfer. and it may turn out to be acceptable.