It is hard to believe that we have been able to record sounds for only a little over one hundred years. Those born after the digital revolution take the ability to make sound recordings entirely for granted. The widespread availability of inexpensive, high-quality recording equipment has greatly increased the number of audio recording practitioners. Although it is easy to get started, many soon discover that attaining the quality of recordings they expect is not as simple as sticking a microphone in front of an instrument and pressing the record button.
Many beginning audio devotees fail to consider the scientific principles behind the techniques professionals use to create the recordings they wish to duplicate. Long internships – once a staple of entry into the recording industry – are vanishing, while more beginners simply start on their own with little or no instruction. Once the difficulty of making great recordings becomes evident, those serious about a career in recording seek out more information. Many schools promise to make the student into a world-class engineer in a few simple lessons, often for a hefty tuition. Simply learning the current techniques without an understanding of why these particular approaches work as they do limits one’s ability to deal with the challenges presented by new recording situations and with the continuing rapid development of recording hardware and software.
Science is a framework used to organize our observations of how the world works. It makes use of mathematics to quantify the behavior of physical objects. It relies on repeatable experiments to verify the theories we formulate about how things work. Although science is applicable to any endeavor that involves physical objects, it is often ignored when we try to figure out how something works. The complexity of mathematics can scare us away from its fundamental usefulness in analyzing the processes we wish to understand. Even without being able to solve differential equations, we can derive a useful understanding of how a system behaves from how the equations are set up and what variables are included. The goal of this book is to show how science explains the techniques we have at our disposal for making and manipulating sound recordings.
Though science is not a static collection of observations, it is a stable source of knowledge. As new discoveries are made, previously accepted ideas are altered to fit both the old and new information. Fortunately, most of the science applied to recording technology is old enough to have been time-tested and proven. It is well worth the effort to learn the scientific principles on which sound recording relies. Areas such as acoustics and electronics are well described and considered settled. Psychoacoustics, on the other hand, leaves much to be explained about how we translate physical air vibrations into musical sound that excites the emotions. The application of the scientific method in our quest to understand the intricacies of recording brings us ever closer to mastering the incredible power we have available to create any sound environment we can imagine.
We will start with a review of the mathematics used in the scientific explanations of acoustics and electronics. The science of measurement is also important because microphones essentially make a measurement of air pressure or velocity that becomes our recorded signal. The ability to quantify physical behaviors is central to building a structured understanding of the systems we use to record sound. The physics of mechanical systems and gases helps understand how microphones transfer sound wave information into electric signals. We also want to understand how we perceive sound, as our ability to hear determines what we must preserve in the processes involved in recording and playing back sound recordings. Of course, sound is at the center of the recording process, and understanding its behavior will begin to explain why microphone placement can be such a tricky proposition. The tools available to process the electronic representation of sounds are at the heart of studio practices. We will look at the passive and active electronic devices, often considered “black boxes,” that make up our devices. Then we will look at the audio processing devices themselves.
Digital recording is the popular technology of the day, but the analog tape recorder was the dominant recording technology throughout the later 20th century and is still popular with rock music studios. Analog recorders, once the mainstay of the recording business, are being discovered by a new generation that appreciates the sound of tape enough to master the care and maintenance of these machines. New magnetic tape is being designed and manufactured to meet the continuing demand. Learning how a mature technology dealt with the limitations of the medium is enlightening.
Digital recording systems have been refined from the days of PCM (pulse-code modulation) to the video converters that began the digital audio age. Digital data is significantly different from the original analog signals that are produced by microphones, so examining the theories underlying digital audio will explain the limitations of analog-to-digital conversion as well as reveal the immense power of digital signal processing. The final chapter involves using all the technical information to accomplish the artistic goals of mixing sounds into the product: recordings for others to enjoy.
This book is not intended to give the reader a mastery of science but rather to reveal how scientific principles apply to the processes we use every day without a second thought. When we understand more of how the systems work, we become better at using them. The reader will find recommended readings that go further into the science of selected subjects to continue the quest we are only beginning here. One of the great aspects of sound recording is that one may enjoy learning the craft for a lifetime. May this book set you on that path.