Pressure Zone Microphone
A unique application of the condenser microphone is the pressure zone microphone (PZM) such as the Crown PZM which has a hemispherical pickup pattern. A miniature condenser microphone is mounted face-down next to a sound-reflecting plate or boundary. The microphone was developed especially for on-surface mounting to avoid the tonal coloration of other types of microphones which are placed close to a surface. The microphone's diaphram is placed in the thin "pressure zone" just above the mounting surface where the incident and reflected sounds combine effectively "in phase" over the audible range. The benefits are a wide, smooth frequency response, excellent clarity, and little off-axis coloration. The "pressure zone" concept comes from the idea that the reflected waves add to the incoming wave. This has the potential for a doubling of effective sound amplitude, which gives four times the sound intensity or a 6 decibel increase in sensitivity.
Sound reproduction concepts
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