Sound Bits and Bytes: An Introduction to Microphones

Abstract

Sound Bits and Bytes: An Introduction to Microphones John L. Butler C. A. S. Figures Click for larger view View full resolution Figure 2. John Butler: “There are no short cuts. You must learn by doing.” Photo by Victor Maysayesva, Jr. As digital audio becomes the established technology for the field, analogue technologies will continue to recede. And even as more recording processes are applicable in both analogue and digital domains, one process remains the same no matter what—“Hind sight is 20/20...future vision is damn near always blind.” Let’s face economic reality: development of new technologies will last as long as SONY and Phillips, for example, are satisfied with their profits; when the market no longer sustains profit ability, it won’t be possible for manufacturers to continue with their same now-old technology, so they’ll introduce a new technology and a new format. In any case, the task of field recording is rapidly changing. I trust that traditional recording standards will not be replaced by cheap machinery and lower standards, such as we see when traditional studio techniques have been replaced by cheap tape recorders, drum machines, and samplers. I like to look at these new machines as missing links or tools to help the recordist to do his or her job well. New technologies of digital audiotape (DAT), the four-track [End Page 37] Nagra-D, Fostex PD2, the 8 track ADAT, and wireless microphones are changing the way production sound and field recordings are produced. The portable analogue reel-to-reel recorders and Nagra machines still remain the field recordists’ basic equipment, but new technologies offer new options for better field recordings. In time, perhaps, new technology may render the standard field recording package nearly obsolete. The old, standard recording package consisted of analogue equipment: a recorder, a mixer, and microphones. The contemporary sound recording field equipment package may use a combination of the best of analogue and digital technologies. Every production is different, and the choice of format may depend on a variety of factors. Given the wide-range of sophistication in available equipment, I could not suggest a specific format without discussing it with the complete production staff—the producer, the director, the director of photography, editors, post production sound mixers, and the lab. We who work in film sound know that we are always eight to ten years behind what [End Page 38] everyone else is doing in the recording world. Most of the studios have a large amount of money invested in traditional technology and are reluctant to change: why change from tried and true recording methods? New sound technology has offered additional freedom to the sound recordist, allowing him or her to be more adventurous and creative in their work. In the past couple years, consumer technology has, in some cases, out-paced professional equipment; this has muddied the field, so to speak, so that the question of whether a format is “consumer” or “professional has no clear answer. I could go on and on about digital versus analogue. While this debate holds interest for some technology buffs, for the sound recorder there are basics that must be mastered, regardless of technological format, that are necessary for getting the best recording for your project. Microphones The microphone is a transducer that converts acoustic energy to electrical energy. This electrical energy, in turn, is amplified and sent to loudspeakers or headphones. Loudspeakers and headphones are another sort of transducer, and their role is to convert this electrical energy back to acoustic energy—back to a sound that we can hear. For accurate sound fidelity, the sound event picked up by the microphone transducer should emerge from the loudspeaker or headphone transducer without any significant change, unless it is an intended change. Click for larger view View full resolution Figure 3. Diagram showing the field of sound sensitivity in a cardioid microphone. Microphones are classified by their patterns. A microphone pattern refers to the shape of the particular area surrounding a microphone, from which the microphone is capable of picking up sound. Thus, we can identify microphones by their directional properties. There are four basic types of microphones: the...