Record vocals everywhere: How to optimize room acoustics for vocal recording

Low noise, no audible room echo – to get high-quality vocal recordings, you have to get a lot of technical and acoustical things right. That can be difficult when tracking vocals in non-ideal environments, whether it‘s your band’s practice space or your singer’s bedroom. But luckily there are certain things you can do to maximize the sound quality of your vocal tracks, even if you’re not in a professional recording studio.

Acoustical criteria

First, let’s define the most important criteria a good recording room should meet for vocals:

No echo: This is probably the most obvious – we don’t want to hear sound literally bouncing around between walls (so-called “flutter echoes”)

Short reverberation/decay time: For maximum flexibility (when processing the tracks later) we need a very dry sound, so we want the room reverberation to be as short as possible, around 0.2s to 0.3s.

Low noise level: No hiss from fans, no hum from electric devices, no ambient/street noise from outside, no rumble from air conditioning

High diffusion: Reflections in the room should be mostly dispersed in many directions. This means that we don’t want reflective areas to be large and flat but rather small and with many different angles. A lot of objects in the room are therefore better than an empty room with blank walls.

Choosing the right room

While this might seem obvious, it’s a step that is often neglected: Now that we know what exactly we’re looking for in our recording room, we want to choose the one that best fits all the criteria above. Further things to watch out for:

Does the room allow mounting acoustic panels on or placing other absorption material at the walls?
Apart from the vocal mic, can you setup your recording rig (computer/laptop, interface, monitors etc.) comfortably in the room?
Does the room allow for a bit of distance between the recording rig and the mic (preferably a few meters away at the other end of the room)?
Does the singer feel good in the room? Do you feel inspired to make music or does the room/location/environment cause you to be cautious and hold back?

Improving room acoustics

Once you’ve decided which room you’re going to use for your recording sessions, you’ll want to make sure you’re getting the most out of it. To do that, you have several tools at your disposal. Let’s start with the most effective and efficient ones first and work our way through all options that are viable solutions in most scenarios.

Absorb flutter echoes at least at one of two opposing walls (floor/ceiling included). You don’t need to cover an entire wall for this, just make sure that there are no directly opposing reflective areas.
Build a provisional vocal booth in a corner of the room through sound absorption. Ideal is a corner that does not have a window directly next to it and and allows for absorption material to be placed at the adjacent walls.
If the room is large and still noticeably reverberant, try reducing the reverb time by placing more absorptive materials in the room, preferably spread evenly on the largest reflective areas (walls/floor).
Don’t use: egg cartons, thin foam (< 5cm / 2“)
Recommended: Basotect or other acoustic foam with a 10cm / 4“ thickness
Echoes between floor and ceiling can be eliminated with thick carpets (or blankets, if not available)
If Acoustic foam is too “permanent“ of a measure, you can still make provisional absorbers: mattress(es), blankets folded and hung on mic stand boom arms, pillows…
Diffusion: If you have decent absorption but you still hear a little reverb and can’t build more absorption into the room, try placing more objects like bookshelves in unused empty spaces of the room. They will scatter reflections and help to absorb them more quickly.

Working "with" the room

This part is about using the circumstances in your room to your advantage, after you’ve set up everything:

Point the mic in the “vocal booth” corner, while pointing the off axis of the mic (with cardioid mics this is the back) to the rest of the room – especially towards any sources of noise (computer fan etc.) Doing this will minimize the “room sound” and unwanted noise in the recording. This works because the sensitive side of the mic is “listening” to the quietest, best treated area of the room while unwanted signals hit the most insensitive side (off axis).
If necessary, rearrange large objects to make space where you need it, while using them to diffuse sound in places you don’t need for your setup.

Do's and Don'ts

Do: Try to tick as many boxes as possible from the tips above. If you have to make compromises, try to start with the least important points. While choosing priorities, still try to balance the measures you take across all the criteria mentioned above. Aim for a balanced sound, even if you can’t make it perfect.

Don’t: Don’t record in a closet! This will sound muffled and muddy in almost all cases. Don’t try to put all effort into one specific aspect of acoustics (e.g. a dry sounding room) while leaving other aspects untouched (e.g. a lot of noise in the room).

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