Reflector Microphones for Field Recording of Natural Sounds

摘要

Directional microphone systems for field recording of sounds in the air usuallyinvolve either a parabolic reflector to focus the sound waves on the microphone (transducer) element, or a linear array of transducers so phased as to respond preferentially to sounds from one directional sector. The latter system (the shotgun microphone) can be analyzed in a fairly straightforward manner. The reflector system involves a structure comparable to a wavelength in linear dimension, and is therefore not susceptible to the conventional approximate methods of computation. Recently developed computational techniques now permit exact calculation of the directional responses of small reflectors. This work computed the characteristics of a number of small microphone reflectors and linear microphone arrays. A flat reflector microphone for the low-frequency range of 10 to 40 Hz was also described. The study concluded that no directional microphone can, in practice, reproduce sounds with fidelity to the sounds as emitted by the source.