By Trent Rentsch
A couple of months ago, we played around with the tone generator and several effects in Audition to whip up a nice little sweeper whoosh. Judging from the positive response, not only are some of you aspiring synthesizer programmers and/or Sound Designers, but you’d like to learn more. Frankly, so would I.
My earliest experiments with synthesizers involved 5% manual reading and 95% knob twiddling. Despite several years of developing both totally creative and absolutely useless sounds, I still hesitated to spend much time with my nose in a book. If you were playing with toys like the DX7 or CZ-101 back in the early ‘80s, you’ll understand and forgive my hesitation. The volumes that came with most synths not only weighed more than the keyboard, but had been translated to English at the plant in Japan by the only staff member to flunk English in grade school. Luckily, it didn’t take some forward thinking authors and publishers long to fill the need for instruction books that, A: laid out the functions and programming of a synthesizer in a simple, yet logical and complete fashion, and B: didn’t read like badly dubbed Godzilla movies.
While many things have changed about electronic noisemakers in the past 20 years, much has stayed the same. The speed and power of computers has increased to the point that the need for an out-board keyboard synthesizer or sampler is nearly obsolete for the studio Sound Designer. These days, my trusty early ‘90s Roland U-20 keyboard is gathering dust on the stand, and the two keyboards that get any work in my studio are the computer keyboard and my MIDI controller, which makes no sound of its own, but “plays” the sounds my software synths make (more about those in a future column). Sadly, what hasn’t changed is the need for more information to learn what makes these computer sound generators click. I literally have mountains of both original instructions and “idiots” guides, and while I’ve pored through them all, the learning never stops. I may not be an expert, but the sounds I’m coming up with are less useless than they once were.
Since some of you have asked for more information, I’m going to spend the next few columns going deeper into the world of electronic noisemakers and what exactly you’re doing when you fiddle with the knobs. If the topic sounds boring to you, hang with me. Even if you have no desire to duplicate the sound of a charging herd of water nymphs with a bank of FM tone generators, you’ll find bits and pieces about the nature of sound that might help you with your everyday audio Creative.
So, here we go. Before we look at how to make sounds synthetically, it’s a good idea to start with a basic understanding of how sound is created naturally. As it turns out, the old joke about what your station Reps sell is true. Basically, it’s all about hot air.
Air is all around us, which is not only important to our basic survival, but also makes sound possible. Mother Nature and gravity attempt to regulate fairly steady air pressure on the planet, but any fast change in that pressure, created by the movement of a solid object (like, say, a forehead smacking a keyboard), makes the air molecules bounce up and down and break dance (just checking to see if you’re still with me). When this air “vibration” between high and low pressure happens, sound waves are created. When the pressure stabilizes, the sound stops. The bigger the vibration, the louder the sound — which is technically measured by “amplitude” (sound familiar?).
So we’ve got a whole lotta shakin’ going on in the air around us, some doing more shakin’ than others. Other than volume, what gives each vibration its own unique “sound?” Another word you’re familiar with, frequency.
As I describe frequency, I don’t want you to panic. There will be numbers involved, but if a guy like me who got hives from High School Algebra can understand it, anybody can. Frequency is the number of times a sound increases and decreases in one second. We use another unit of measurement familiar to anyone in radio to describe these vibrations or cycles, our old friend the Hertz. If a sound bounces completely up and down (or “cycles”) 6 times in one second, its frequency is said to be 6 Hertz (or 6Hz, for short). If the vibrations jump up in the thousands, we add kilo to Hertz. So, if a sound bounces completely up and down 2000 times in one second, its frequency is 2 kiloHertz, or 3 kHz. See, not so tough, school’s out, give yourself an A.
Funny thing about the human ear, it evolved only enough to perceive the frequencies that would pose a threat to us. So because our early predators rumbled, growled, roared, hissed, and shrieked somewhere between 20Hz and 20 kHz, the average person can only hear sounds between those ranges (which means you probably aren’t hearing the subwoofer in the neighbor kid’s car so much as the higher frequency rattle of the windows in your house as he drives by).
So, we know what makes up sound, what makes it softer or louder, and what gives it a unique “tone,” and which ones we’re capable of hearing. Well, sort of. If it were that simple, the sound palette wouldn’t be so rich. Most sounds are made up of many different frequencies, all with different amplitudes, beginnings and endings. These ingredients for sound are called sine waves. I’ll spare you the pain of trying to explain the math behind sine waves (yeah, like I could). Suffice to say, a sound might have, for example, one long frequency at 50 Hz, another softer one at 372 Hz, and a short, quick one at 852 Hz. Put them all together and you have one sound, possibly the result of my lunch trip to the Mexican buffet, but I could be wrong…
Next month, a few more words about sound in the real world and the history of unreal ways to create it.