A topic in the Open Knowledge Graph — a free, open map of 15,290 topics and the order to learn them in.
A microphone is a transducer that converts acoustic pressure variations (sound) into electrical signals. Different transducer technologies and polar patterns make microphones suited to very different recording situations, and choosing the right mic for a source is one of the most consequential decisions in recording.
The three dominant transducer types each have distinct characteristics. Dynamic microphones (like the Shure SM57 and SM58) use a moving coil attached to a diaphragm — sound pressure moves the coil through a magnetic field, inducing current. Dynamics are robust, handle high SPL (sound pressure levels) without distorting, require no power, and have a natural high-frequency roll-off that suits loud sources like guitar cabinets and snare drums. Condenser microphones use a thin charged diaphragm near a backplate — sound pressure changes the capacitance and generates voltage. Condensers are more sensitive, have wider and flatter frequency responses, and capture transient detail better, making them preferred for acoustic instruments, vocals, and overheads. They require phantom power (+48V). Ribbon microphones use a thin corrugated metal ribbon in a magnetic field. Ribbons have a natural figure-8 polar pattern, warm high-frequency rolloff, and excellent transient response — they are prized for brass instruments, room ambience, and vintage vocal sounds, but are fragile and can be damaged by phantom power.
Polar patterns define which directions a microphone is most sensitive to. Cardioid picks up primarily from the front, rejecting the rear. Supercardioid and hypercardioid are narrower, with small rear lobes. Omnidirectional picks up equally from all directions — useful for capturing room sound and free of proximity effect. Figure-8 (bidirectional) picks up front and back equally, rejecting the sides — used in mid-side (M/S) stereo recording and as ribbon microphones' natural pattern.
Placement technique dramatically affects the recorded sound. The proximity effect — a bass boost that occurs in directional microphones as the sound source moves closer — can be used intentionally for warmth or managed to avoid excessive low frequencies. Distance from the source determines the ratio of direct sound to room reflections; closer placement captures more detail and isolation, while further placement captures more natural room ambience.
Microphone selection and placement is where a recording begins — every subsequent processing decision is shaped by the quality and character of the initial capture. A great microphone placement in a good-sounding room with an appropriate mic for the source will always yield better results than extensive corrective processing downstream.
Recording technique encompasses not just microphone choice but room treatment, source positioning, and the psychological management of performer comfort in the recording environment. Session engineers learn to assess each situation — source level, room acoustics, desired tonal character, isolation requirements — and make a rapid, informed placement decision.
Stereo recording techniques like spaced pair (AB), coincident pair (XY), near-coincident (ORTF), and mid-side (M/S) use multiple microphones to capture a natural stereo image. Each technique makes different tradeoffs between stereo width, mono compatibility, and phase coherence. Understanding these techniques, along with transducer and polar pattern characteristics, forms the foundational vocabulary of recording practice.
Topics in reflective domains aren't scored by quiz answers. Read, reflect, and mark when you've thought it through.