Vocals are, as you have become used to me saying, made up of multiple sounds. Look at a head.

Here are a set of cavities. The throat, the mouth, the nasal cavity etc. Each has a size which resonates at a certain pitch and they are joined up in sequence. If you are Barry White your big cavities are resonating low, and if you are me, not so much. As Barry sings, he creates a fixed note cluster that colours the notes he sings, which is the formant. If you are Warren Burt or Diamanda Galas you have learned how to produce two notes at once by independently resonating your nasal cavity. Others may have perfected borbarigmus, I hide their secret here.

The tone of your voice stays much the same no matter what note you sing (although different volumes and stresses accent different cavities). Pitch shifting the voice up and down unnaturally shifts this tone such that you get the familiar ‘giant’ and ‘chipmunk’ side effects. Modern samplers and Pro Tool’s pitch shifter offer a formant adjustment that compensates for this, keeping the cavity sizes constant when shifting the pitch. Also you may impose an artificial formant on a voice to create a larger or smaller vocal apparatus – the basis of voice changer software.

Recording in a room captures not only the sounds you’re after but the tone of the room, the resonance of the room itself. Which is is why when you come back and redub dialogue into a film work it may be  unconvincing – just as reshooting under a different temperature of light will look wrong, recording in a studio won’t match up with the live sound. You need to always capture a little ‘air’ from your location to cover the rerecorded sections and very likely will have to EQ the ADR voice to try match the tone of the room. Very often once you’ve identified the room’s pitch you can create a peak (increased volume closely around a certain frequency) in the EQ that is similar – although notches (decreased volume) have sometimes worked better for me, and often as comb filters – it depends on the nodes in the room – more later.

Musicians should be aware of the resonance of the room when finding the best place to record an instrument – singing in the shower – or like Joy Division, recording the drums on the roof. Flat acoustics are not always the best.

3D animators (only those poor souls that have to do their own sound design) need to think of the rendering of sound as much as the vision. I ask my 3D kunstlers to use a fixed flanger (which is a kind of comb) on all the foley in their space epics to create the metal walls and floor we’re seeing on screen. Done right, the reality is much more powerful.

There are holes in the head for the gas to get out – cake hole and two nose holes (ears don’t count). They add more upper ‘air’ to the sound as the breath collides with tounge and teeth and lips. One is able to sing more through the nose or mouth. You can even sing with both closed. Try blocking each and listen to the ‘submixes’ of your voice. (Please remember to unblock nose and mouth when finished).

When we sing louder the formant shifts slightly and we add more or less noise into our mix. One popular trick especially with female singers is to add a little white noise into their vocals, expanded by the amplitude of the voice. This breathy voice sounds more passionate and intimate – as if close mic’ed but without the bass shift that brings. Compressing the voice can also be used to apparently shift the emphasis and was a major part of being a Beatle.

Recording dialogue in a room is therefore quite tricky – resonances everywhere, microphone placements causing filtration etc. It’s suprising how often people get decent results, but they do. Getting beyond that takes years of listening and experimentation. As an engineer you have to think like a director of photography, but instead of seeing light and layout, you have to hear the tone of the space, the sounds from outside the space and the way the voices reflect off the surfaces. And more.

Go to the space, close your eyes. Listen.