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The sound quality of the sound source may potentially be altered by close microphone placements. As above, these alterations can be used to creative advantage, or they can distort the desired sound quality. The sound quality may exhibit the following alterations, when the source is close miked:
• An increase of definition over known, naturally
occurring degrees of timbre detail
• Changed spectral content of the sound source
• An unnatural blend of the source's timbre, caused when
the source has not had enough physical space to develop into its characteristic sound quality
A microphone placed within two feet of a sound source may alter the source's spectral content. The frequency response of certain microphones are altered by the proximity effect. Response in the low frequency range rises relative to response in higher frequencies, for cardioid and bi-directional microphones.
The sound source itself and the way it radiates sound, along with the producer's idea of what it should sound like, must also be considered in the context of the sound's environment.
Sound sources require physical space for their sound quality to develop or coalesce. The sound quality of instruments and voices is a combination of all of the sounds the instrument produces. When a microphone is placed in a physical location near the sound source, it will often be within this critical distance necessary for the sound to develop into a single sound wave. The sound source will not have had the opportunity to blend into its unique, overall sound quality. Only a portion of the sound will be captured by the microphone. This sound quality will be very different from our experiences of how the sound source appears in acoustic environments.
It is not unusual for recordists to capture a sound before its characteristics acoustic sound has fully developed. This can be accomplished in such a way as to contribute to the music, or it may work against the project. It is important that the recordist be aware of this space, and in control of recording the desired blend of the source's sound.
Many instruments, and voices, are commonly recorded with close microphone techniques, capturing only a portion of the source's characteristic timbre. Care must be taken to obtain the desired sound quality; many undesirable noises are created by performers and their instruments, that may cause difficulties in obtaining a suitable sound.
In close micing sound sources, all or most natural environmental cues are absent from the sound. Environmental characteristics will be added to these sources through signal processing. Electronic or amplified instruments that are plugged directly into the mixing console (through a direct box) are similar in their lack of environmental characteristics. If the listener is to be provided with a realistic listening experience (which may or may not be desirable), environmental characteristics need to be added to these sounds.
Recordists often capture the sound of a sound source from a number of close microphone locations, and to blend the sound themselves. This can be performed to great creative advantage; the recordist may control the blend of the various portions of the source's sound, instead of relying on the sound source's interaction with the performance environment to blend the sound as desired. Pianos are commonly recorded in this way, as are acoustic guitars; this technique can be applied to a wide variety of sound sources.
Sound sources (individual instruments/voices or ensembles) may go through a conceptual pre-processing with the application of microphone techniques. Pre-processing is an alteration to the components of the sound source before it has become available in the routing and mixing stages of the recording chain.
A stereo microphone array is the use of two or more microphones, in a systematic arrangement. A stereo microphone array is designed to capture the sound in such a way that upon playback of the recording, through two loudspeakers, an accurate sense of the spatial relationships of the sound sources present during the recorded performance is reproduced in playback. The techniques attempt to capture the sound qualities of the live performance and of the hall, the performed balance of the instruments of the ensemble, and the spatial relationships of the ensemble (stereo location and distance cues), with minimal distortion
Stereo microphone techniques are often used in recording large ensembles, in large acoustic spaces, from a rather distant placement. The techniques are very powerful in their accuracy and flexibility, may be applied to either a single sound source or to any sized ensemble; they may be used from a rather distant placement (perhaps fifteen or more meters, depending on the pertinent variables), to within about a meter of the sound source (stereo arrays are commonly applied to drum sets, sometimes supplemented with accent microphones, sometimes not).
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