Acoustic foam soundproofing for the home?

In My Humble Opinion
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1

I’ve decided to pick up singing again, and am taking voice lessons now. Part of my homework is practicing at home to better learn breath control, etc. Sometimes that requires singing at a normal or louder volume, but I don’t really want to bother my next-door neighbor.

In music classrooms and recording studios, you often see acoustic foam tiles like this, the spiky mini-pyramids or ridges like this:

I know they’re available online, but I’ve never tried installing them on my own. Do I need to be concerned about their specific material (both in terms of sound dampening and potential fire risk, etc.), their size, or placement?

Like do I need to position them in any particular sort of pattern to best attenuate the sound of a human voice (in terms of wavelength, etc.), or is it more or less just “grab a bunch and stick them wherever”?

Bonus question: Are there any that are somewhat prettier, like maybe acoustic foam with landscapes or art printed on them?

2

Hmm. The internet is also saying that foam doesn’t actually block sound transmission through walls, merely reduce echoes within the room. Is that true…? e.g. I understand that acoustic foam aren't meant to block sound but I'm in a large room with lots of echo, so technically if I can kill some of that echo would it not also reduce the sound coming out of that room a bit? : livesound

They apparently also make portable “vocal booths”:

And, um… voice condoms…?

A bit ridiculous-looking, but I wonder if that would work better?

3

I came here to say just that. Those cones just make your voice “dry” so basically do take out Echo and Reverb but won’t lower what your neighbor is going to hear.

4

Going back to the acoustic panels, you would need to cover the entire wall in your neighbour’s direction, every square centimetre without exception, to make any difference. Any through-path whatsoever will make the rest pointless.

And depending on the setup of your place vs theirs, you may need to do at least part of the side walls, ceiling and floor too.

5

I installed a lot of those sawtooth foam panels on the walls and ceiling of my classroom before I retired - they made the room much more comfortable (especially when filled with active Middle School students). But as noted, they do nothing to reduce sound transmission.
I’m currently putting mineral fiber batts in the ceiling of the playroom I dug out of the crawlspace under the house, and they DO make a big difference in sound transmission. Grandchildren can make a racket.

6

Definitely consider fire risk. There was recently that deadly Swiss bar fire on NYE from sparklers which ignited the acoustical foam panels on the ceiling. There were videos of the ceiling catching fire and it was shocking how quickly the fire spread. And it can produce lots of thick, toxic smoke. Hopefully there’s never a fire, but if there is, you want to minimize the effect that the foam can have.