Just out of curiosity, does the acoustic treatment have much effect on the vocal recording? I am currently just sitting on the floor of my dining room for vocals with some furniture for absorbtion. Curious to hear your thoughts. Take care. Greg
This has several factors for consideration.
1. Pickup pattern and gain of the microphone. Microphones with more off-axis rejection, will be less sensitive to reflections in the room, and therefore need less concern about acoustic treatment. I can record my vocals and acoustic guitars in my living room with my SM58 knock-off or my EV PL1 with very little concern about reflections.
2. A big concern with home studios is reflections off of nearby surfaces. One major faux pas of home recordists is to record into a mic that is on their desk, where they have their computer monitor basically in a line between their mouth, the mic, and the screen. Of course it's tempting to do this, you can look at your music while you sing. This can result in a very unpleasant comb filtering, as the sound bouncing off the screen comes back to the mic with a slight time delay, and notches out frequency content due to some of the frequency content being out of phase with the direct sound. The furniture you refer to should be highly absorbent, even taught tightly woven cloth and particularly vinyl/leather can be quite reflective. You want pillow/blanket soft, nothing tight woven or shiny. Shiny normally means acoustically reflective as well as reflective to light.
Here's a weird outcome of this. Leather seats in cars - used to be for luxury cars only. The same vehicle with cloth seats instead of leather seats, is quite a bit more quiet in the interior. This is one of the reasons you see perforated leather surfaces used commonly now in seats. If you can order the exact same content in a vehicle and opt out of leather seats, it will be generally quieter in the interior.
3. Sitting versus standing - you can project better standing, usually. This is normally good, but also means you probably are putting more acoustic energy into the room, which can reflect back to the mic - so sitting might actually help the overall recording situation, but perhaps not the vocal performance!
I agree with chulaivet, I prefer to record in an acoustically dead space at home, and then add in reverb. If I can get rid of most nearby (within a few feet) reflective surfaces, I can record a better sounding vocal. This also includes the ceiling - one surface often forgotten. In my setup below, I have a big comforter that I throw over the top of that GOBO, and safety-pin it to the clothes rack inside the closet. Reflections from ceiling - gone.