Vocal Recording, Pt. Two: Recording Space
By Mitchell Sigman
In our last entry, we talked about the gear needed to record pro—sounding vocals. This time around, we’ll talk about the recording environment. The two most important factors here are having a space that’s relatively quiet and sounds good.
Keep It Down: Soundproofing vs. Room Treatment
First, let’s talk about the “quiet” part of the equation. In a typical domestic space, there’s usually not a whole lot you can do to 100% soundproof a room. If the recording space is subject to noise that’s out of your control, i.e. passing trucks, airplanes, etc., you could opt to soundproof a space. But many don’t have a clear understanding of the difference between soundproofing and acoustic room treatment. People often mount acoustic foam (or egg crates, blankets, curtains, etc.) to the walls of their recording space and believe they’ve “soundproofed” the space. The truth is that the only way to effectively soundproof a space is with mass, usually in the form of walls. In a home studio, this is usually done by building an entirely new subfloor on top of the existing floor (usually atop rubber “bumpers”), then building entirely new walls inside the existing structure (usually about a foot within the outside walls). This gets topped off with a new “floating” ceiling. Once you’ve built and tightly sealed all this, HVAC must be dealt with to prevent air leaks that can transfer sound (while still providing adequate fresh air), thereby defeating the purpose of all this custom construction. As you can see, proper soundproofing can quickly get complicated (and pricey). The good news is that for most pop/rock music production, a 100% silent room isn’t necessary, because distant background noises probably won’t be audible in the context of a full mix.
Make The Room Sound Good
This is the part of the equation that a home recordist has a fair amount of control over. Remember the acoustic foam we talked about above? Its main mission is to prevent sound waves from bouncing around a room in an uncontrolled, chaotic fashion (Chaotic Fashion is a super—rad fictional 1978 punk band name). Specifically, an untreated room with parallel walls will usually suffer from a bad case of standing waves. A standing wave is a resonant “node” that causes a room to ring at specific frequencies – this is caused by wide and flat, reflective wall surfaces and the specific dimensions of the room. If you’re ever sung in the shower, you’ve experienced this. Though you may sound like George Michael in the shower, for realistic vocal recordings, we want a flat frequency response without exaggerated, frequency–specific echoes. Conversely, if you’re ever been inside a purpose–built, high–end recording studio, look at the arrangement of the walls or the glass in the control room – they’re always at angles. This is done to prevent standing waves.
Acoustic foam, or thick packing blankets can effectively mitigate standing wave echo. Believe it or not, any large, substantial object (like a couch or big studio rack) can help absorb and/or disperse standing wave energy. This is why a big, parallel-walled empty room is the worst for standing wave echoes (think of a racquetball court).
I’ll usually walk around a room clapping my hands to find the “hot spots,” then put up acoustic foam on a nearby wall. It’s not a super—exact science, but the idea is to arrive at a happy medium of live vs. dead room. Putting foam on every square inch of wall space will create an artificially dead space, so don’t go too crazy. Be aware that it’s usually not necessary to place foam in similar locations on parallel walls, because you only need to stop the sound wave from bouncing in one direction (hey, another awesome band name!).
Super No—Extra—Charge Not—Related—To—Singing–Room Tip:
Because of limitations of room size, home recordists often set up monitor speakers against walls or in corners. This is great for maximizing space, but awful for acoustics. Sound (especially bass) tends to “couple” and build when speakers are near walls, and even moreso in corners. If you’ve ever played back bassy material and found that, “the bass sounds great right here!,” the truth is probably the opposite. Bass frequencies may sound loud in that particular location, and in all likelihood bass frequencies will be subdued a foot or more away. This is more standing wave shenanigans in action, only at lower frequencies, because the sound wavelengths are long enough to walk in and out of the “hot spots.” The truth is that neither the exaggerated or subdued points are truthfully representing the sound. Acoustic room treatment can help, but in small rooms (less than around 150 sq ft), it’s almost impossible to monitor bass properly. That said, getting speakers at least two feet away from walls, and pointing them down the longest dimension of the room will make for a much truer monitoring experience.
People like to use vocal booths because they offer increased isolation not only from extraneous outdoor noise, but from the more “local” sound pollution of the engineer operating a DAW or moving in their seat. The downside of some vocal booths (such as coat closets) is that they don’t always sound that great. If they have a lot of undamped hard surfaces, they can quickly starting sounding like the aforementioned shower stall. Something a little larger than a coat closet usually sounds better, and I strongly recommend giving it the “clap test” to make sure there aren’t any weird resonances. If you do run into this, you can probably improve the situation with acoustic foam or packing blankets on a wall or two. But be careful, because you don’t want a totally dead room. Not only do they not record that well, but if the singer feels like they’re singing into a pillow, their performance will likely suffer.
Noise, Vibration, and Harshness
When I was a wee lad of 16 or so, MTV used to incessantly play the Guns ‘n’ Roses “Patience” video and I used to chuckle at how you mysteriously never had the racket of Axel Rose’s 23 pounds of bangles, crosses, and dangly belts clanging away as he poured his guts out in the faux—studio. Sometimes this can become a reality, so it’s up to you to make sure a singer’s accessorizing habits don’t compromise the recording. Some taps and thumps will be eliminated by using a shock mount with the mic, but not all, so keep your eyes and ears open for habits like loud foot tapping (especially on wood floors), finger snapping, or any other extraneous expressions you don’t want recorded with the take. Singers probably won’t like being nitpicked for their noise, but in the end, better recording = happier singer!