Essentials of Sound by Marc Schonbrun
As a recording engineer in training, you'll have to know a little bit about sound waves and electricity, because they are pivotal to understanding recording. In this chapter, you'll see why music can't be separated from science—the terminology is everywhere, impossible to escape. Have no fear!
Sound Waves
Sound is emitted by a source and travels in waves that vibrate back and forth, pushing air molecules around them. The sound waves create sound pressure (volume) as they push through the air molecules, which make our eardrums vibrate and pick up sound. Without a medium for sound waves to travel through, there is no sound.
Sound needs a medium to carry its waves: air, water, and the earth itself can all transmit sound. Certain media carry sound better than others; you might notice that it's more difficult to hear under water than it is on dry land. In space there is no sound, because in a vacuum, there is nothing to transmit sound.
The speed that a sound source (a monitor speaker, for example) vibrates tells you the frequency of the sound that comes out. If a speaker is playing a perfect A (440Hz) tuning note, such as one found on metronomes and tuners, it is vibrating back and forth 440 times a second. The faster the source vibrates, the higher the sound; the slower it vibrates, the lower the sound, or pitch, you hear. Sounds are rarely made up of just one frequency; actually there are many frequencies present in any one sound. The science behind it is beyond the scope of this book, but just understand that when you play or sing one note, there's more than just one frequency present.
You might be saying to yourself, why do I have to know this? That's a legitimate question, and here's the short answer: Understanding frequency and how sound works is essential to mixing and almost all effects. We don't just talk about “low sounds;” you'll see on your EQ knob that “low” might have “80Hz” next to it. Your microphone might have a “100Hz roll off” on it. You might read an article about boosting the 10kHz band to improve presence and clarity. Wouldn't you like to know what that all means? Simply put, the audio community, of which you are now a full-fledged member, deals with terms like hertz and kilohertz, so you should learn what they mean to avoid confusion!
Ranges of Sound
Let's talk a bit about the ranges of sound you may be used to. Your stereo might have a bass and treble knob. These knobs are used to boost or cut a certain range of frequencies. The specific range of frequencies involved will differ from system to system, but the process is generally known as equalization (EQ). Equalization is simply the boosting or cutting of certain frequencies of a sound. The most basic EQ you will encounter is a three-band EQ on a mixer (either outboard or virtual).
Figure 15-1: Mixer EQ Controls
As you can see in Figure 15-1, there are values in Hz next to the knobs. The values show what ranges of sounds are affected by turning those knobs. If you really want to learn about EQ, twist knobs and listen. Like any other skill, you need to practice. Don't be afraid to turn knobs and listen to what happens.
Effect Types
Studios use a few different types of effects. The first, EQ, isn't really an effect per se, but for our purposes, we'll lump it in with the rest. There are many flavors of EQ, from a simple three-band EQ found on many four-tracks and mixers to elaborate parametric equalizers that give a great deal of control over individual frequencies. Dynamic processing involves effects that control the volume or dynamics of sounds. Effects like compression, limiting, gating, and expanders all control the volume of tracks.
Special effects usually encompass delay and its many incarnations, such as tape delay and multitap delay. Modulation effects like chorus and phasers and flangers change the sound by utilizing a delayed signal mixed in with the original signal, which either delays that signal or changes how the delayed signal sounds.
Reverb is the most important effect to learn how to utilize well. Every sound we hear has some reverb. Reverb, which is short for reverberation, is a natural occurrence when sound waves reflect and bounce off surfaces. The larger the room, the longer it takes the sound to come back to your ears—giving you the feeling of space and distance. Reverb is such an important part of acoustic sounds that when we record without it, it sounds quite strange.
Hardware Versus Software
Years ago, effects were done exclusively by rack-mounted outboard effects units. Certain effects processors were multifunction units and could produce reverb, delay, and other effects all within one unit. Other gear, like a compressor, performed one specialized job. The great part about outboard gear is that it sounds really good.
Even with the innovations of software plug-ins, many professional engineers opt for tried-and-true hardware devices over plug-ins. Some of this is habit, and some of it is because hardware just sounds better. When you walk into a professional studio, notice the many racks of hardware devices still in use today.
Early outboard gear used analog technology to produce effects. As technology improved, manufacturers turned to digital signal processing (DSP) chips to improve the quality of the sound. The digital-effects processor was born. It was only a matter of time before a computer was able to do the job of DSP. Indeed, that day has come. Now, instead of needing floor-to-ceiling racks of gear, you can re-create all the effects you want through software. This is where the home studio became powerful. No longer do musicians need all the space and expensive gear they used to! Through software, a computer can do it all.
